ツイッター新機能がAPIに反映されているか：写真へのタグ付けと写真4枚添付可能（5/31 APIに新機能追加されました）

新APIがまだ公開されていない時点での元エントリ → 本編

更新情報（5/23以降）

西海岸（太平洋）夏時間5/28~~（の0時）~~（日本時間5/28 ~~16時~~）に写真複数添付機能がAPIに追加されます。

On May 28th PDT (UTC-7) we will launch support for composing tweets with multiple images via the REST API. Details: https://t.co/XB1rnLfFmo
— Twitter API (@twitterapi) May 22, 2014

追加されるAPIの詳細はこちら。

Multiple Media Entities in Statuses | Twitter Developers

ポイントは

APIの返答に、写真へのリンク情報が含まれていた"entities"に加えて、"extended_entities"が加わります
"extended_entities/media"の第1要素は"entities/media"と全く同じ（多分）
写真以外のメディアの添付が可能になる（かも）
メディア数が4つ以上の添付が可能になる（かも）

「かも」付けしてあるのは、まだ不明な項目です。

追記：5/28 1時〜2時

写真が複数枚添付されているTwitter::Tweet インスタンスをmultiphototweetと書くことにすると、entities以下のmediaにある要素についてTwitter gem(v. 5.9.0)では以下のようなアクセスが行えます。

> multiphototweet.media.first.attrs
=> {:id=>449746301068926976,
 :id_str=>"449746301068926976",
 :indices=>[118, 140],
 :media_url=>"http://pbs.twimg.com/media/Bj3R4MJCYAAqnMg.jpg",
 :media_url_https=>"https://pbs.twimg.com/media/Bj3R4MJCYAAqnMg.jpg",
 :url=>"http://t.co/Mljw3xOY3B",
 :display_url=>"pic.twitter.com/Mljw3xOY3B",
 :expanded_url=>
  "http://twitter.com/riocampos/status/449746301857447936/photo/1",
 :type=>"photo",
 :sizes=>
  {:medium=>{:w=>600, :h=>537, :resize=>"fit"},
   :small=>{:w=>340, :h=>304, :resize=>"fit"},
   :thumb=>{:w=>150, :h=>150, :resize=>"crop"},
   :large=>{:w=>640, :h=>573, :resize=>"fit"}}}
> multiphototweet.media.first.media_url
=> #<Addressable::URI:0x3fdd89580920 URI:http://pbs.twimg.com/media/Bj3R4MJCYAAqnMg.jpg>

extended_entities/mediaの第1要素はentities/mediaと同じっぽいので、Twitter gemは今後のアップデートでTwitter::Tweet#mediaをextended_entitiesのなかのmediaを取得するように変更するはずです。
とはいえ、いままでのTwitter gemでも、Twitter::Tweetオブジェクトに対してTwitter::Tweet#attrs（または#to_h）でシンボルをキーとしたハッシュを返してくれます。これはJSONをそのまま展開しているだけです*1。なので

multiphototweet.attrs[:extended_entities][:media].first

で1枚目の写真に関するハッシュ（multiphototweet.media.first.attrsおよびmultiphototweet.attrs[:entities][:media].firstと同じハッシュ）が取得できる、と推測されます。
~~全ては、日本時間5/28 16時に明らかになります。~~

5/28〜29追記

（~~5/28~~ ~~16時半~~ ~~18時~~ ~~20時~~ ~~23時半~~ 5/29 1時 ~~2時半~~ 現在、まだ追加されていません。）

5/29 11時追記

残念ながら5/29の西海岸夏時間の業務時間帯の更新になるようです。
「実は、明日5/29の業務時間帯のリリースになります。今日は一日通して準備の予定です。」

日本時間5/29 9:18の投稿でした。
5/29の西海岸夏時間の業務時間帯を9〜17時と仮定すると、日本時間だと5/30 1〜9時になります。

5/30追記

「ロールアウトは明日5/30の終わり（太平洋夏時間17時）までに終える予定」

日本時間5/30 9時頃の投稿。
5/30 17時は、日本時間だと5/31 9時に相当します。

5/31 12時追記：新APIが有効になりました

Twitter gemでのアクセスでもextended_entitiesが見れてます\o/

multiphototweet = client.status('449746301857447936')
multiphototweet.attrs
=> {:created_at=>"Sat Mar 29 03:14:08 +0000 2014",
 :id=>449746301857447936,
 :id_str=>"449746301857447936",
 :text=>
  "タグ付けされた側は通知が来る。そしてタグ付けを含むツイートには（ツイートした垢が鍵付きじゃなければ、タグ付けに関係しない垢からも）タグ付けされた垢名を確認できる。\n新機能の写真タグ付けに加え、写真は1ツイート4枚まで追加可能になった。 http://t.co/Mljw3xOY3B",
 :source=>
  "<a href=\"http://twitter.com/download/iphone\" rel=\"nofollow\">Twitter for iPhone</a>",
 :truncated=>false,
 :in_reply_to_status_id=>nil,
 :in_reply_to_status_id_str=>nil,
 :in_reply_to_user_id=>nil,
 :in_reply_to_user_id_str=>nil,
 :in_reply_to_screen_name=>nil,
 :user=>
  {:id=>56997313,
   :id_str=>"56997313",
   :name=>"riocampos（りおかんぽす）",
   :screen_name=>"riocampos",
   :location=>"Osaka, Japan",
   :description=>
    "plz call me rio☆ favorite: cycle road race & figure skate, Mac!, iPhone!, Ruby, Fine-Art, Science, Black/Green Tea. | Gender:♂ (FB: http://t.co/71QgiSwca0 )",
   :url=>"http://t.co/cRXTvrEpoN",
   :entities=>
    {:url=>
      {:urls=>
        [{:url=>"http://t.co/cRXTvrEpoN",
          :expanded_url=>"http://about.me/riocampos",
          :display_url=>"about.me/riocampos",
          :indices=>[0, 22]}]},
     :description=>
      {:urls=>
        [{:url=>"http://t.co/71QgiSwca0",
          :expanded_url=>"http://on.fb.me/MvEV7P",
          :display_url=>"on.fb.me/MvEV7P",
          :indices=>[132, 154]}]}},
   :protected=>false,
   :followers_count=>2121,
   :friends_count=>2326,
   :listed_count=>191,
   :created_at=>"Wed Jul 15 12:02:35 +0000 2009",
   :favourites_count=>2947,
   :utc_offset=>32400,
   :time_zone=>"Osaka",
   :geo_enabled=>true,
   :verified=>false,
   :statuses_count=>182200,
   :lang=>"en",
   :contributors_enabled=>false,
   :is_translator=>false,
   :is_translation_enabled=>false,
   :profile_background_color=>"48E0B7",
   :profile_background_image_url=>
    "http://pbs.twimg.com/profile_background_images/378800000158576090/WjPzbAXY.jpeg",
   :profile_background_image_url_https=>
    "https://pbs.twimg.com/profile_background_images/378800000158576090/WjPzbAXY.jpeg",
   :profile_background_tile=>true,
   :profile_image_url=>
    "http://pbs.twimg.com/profile_images/3462273402/f331afb1b57c7d39688229e86de95881_normal.jpeg",
   :profile_image_url_https=>
    "https://pbs.twimg.com/profile_images/3462273402/f331afb1b57c7d39688229e86de95881_normal.jpeg",
   :profile_banner_url=>
    "https://pbs.twimg.com/profile_banners/56997313/1365179721",
   :profile_link_color=>"009999",
   :profile_sidebar_border_color=>"FFFFFF",
   :profile_sidebar_fill_color=>"EFEFEF",
   :profile_text_color=>"333333",
   :profile_use_background_image=>true,
   :default_profile=>false,
   :default_profile_image=>false,
   :following=>false,
   :follow_request_sent=>false,
   :notifications=>false},
 :geo=>nil,
 :coordinates=>nil,
 :place=>nil,
 :contributors=>nil,
 :retweet_count=>0,
 :favorite_count=>1,
 :entities=>
  {:hashtags=>[],
   :symbols=>[],
   :urls=>[],
   :user_mentions=>[],
   :media=>
    [{:id=>449746301068926976,
      :id_str=>"449746301068926976",
      :indices=>[118, 140],
      :media_url=>"http://pbs.twimg.com/media/Bj3R4MJCYAAqnMg.jpg",
      :media_url_https=>"https://pbs.twimg.com/media/Bj3R4MJCYAAqnMg.jpg",
      :url=>"http://t.co/Mljw3xOY3B",
      :display_url=>"pic.twitter.com/Mljw3xOY3B",
      :expanded_url=>
       "http://twitter.com/riocampos/status/449746301857447936/photo/1",
      :type=>"photo",
      :sizes=>
       {:medium=>{:w=>600, :h=>537, :resize=>"fit"},
        :small=>{:w=>340, :h=>304, :resize=>"fit"},
        :thumb=>{:w=>150, :h=>150, :resize=>"crop"},
        :large=>{:w=>640, :h=>573, :resize=>"fit"}}}]},
 :extended_entities=>
  {:media=>
    [{:id=>449746301068926976,
      :id_str=>"449746301068926976",
      :indices=>[118, 140],
      :media_url=>"http://pbs.twimg.com/media/Bj3R4MJCYAAqnMg.jpg",
      :media_url_https=>"https://pbs.twimg.com/media/Bj3R4MJCYAAqnMg.jpg",
      :url=>"http://t.co/Mljw3xOY3B",
      :display_url=>"pic.twitter.com/Mljw3xOY3B",
      :expanded_url=>
       "http://twitter.com/riocampos/status/449746301857447936/photo/1",
      :type=>"photo",
      :sizes=>
       {:medium=>{:w=>600, :h=>537, :resize=>"fit"},
        :small=>{:w=>340, :h=>304, :resize=>"fit"},
        :thumb=>{:w=>150, :h=>150, :resize=>"crop"},
        :large=>{:w=>640, :h=>573, :resize=>"fit"}}},
     {:id=>449746298007076864,
      :id_str=>"449746298007076864",
      :indices=>[118, 140],
      :media_url=>"http://pbs.twimg.com/media/Bj3R4AvCQAA9-Le.jpg",
      :media_url_https=>"https://pbs.twimg.com/media/Bj3R4AvCQAA9-Le.jpg",
      :url=>"http://t.co/Mljw3xOY3B",
      :display_url=>"pic.twitter.com/Mljw3xOY3B",
      :expanded_url=>
       "http://twitter.com/riocampos/status/449746301857447936/photo/1",
      :type=>"photo",
      :sizes=>
       {:medium=>{:w=>599, :h=>1024, :resize=>"fit"},
        :large=>{:w=>599, :h=>1024, :resize=>"fit"},
        :thumb=>{:w=>150, :h=>150, :resize=>"crop"},
        :small=>{:w=>340, :h=>581, :resize=>"fit"}}},
     {:id=>449746298887868416,
      :id_str=>"449746298887868416",
      :indices=>[118, 140],
      :media_url=>"http://pbs.twimg.com/media/Bj3R4EBCEAAUIgg.jpg",
      :media_url_https=>"https://pbs.twimg.com/media/Bj3R4EBCEAAUIgg.jpg",
      :url=>"http://t.co/Mljw3xOY3B",
      :display_url=>"pic.twitter.com/Mljw3xOY3B",
      :expanded_url=>
       "http://twitter.com/riocampos/status/449746301857447936/photo/1",
      :type=>"photo",
      :sizes=>
       {:small=>{:w=>340, :h=>604, :resize=>"fit"},
        :large=>{:w=>576, :h=>1024, :resize=>"fit"},
        :thumb=>{:w=>150, :h=>150, :resize=>"crop"},
        :medium=>{:w=>576, :h=>1024, :resize=>"fit"}}}]},
 :favorited=>false,
 :retweeted=>false,
 :possibly_sensitive=>false,
 :lang=>"ja"}

multiphototweet.attrs[:extended_entities][:media]
=> [{:id=>449746301068926976,
  :id_str=>"449746301068926976",
  :indices=>[118, 140],
  :media_url=>"http://pbs.twimg.com/media/Bj3R4MJCYAAqnMg.jpg",
  :media_url_https=>"https://pbs.twimg.com/media/Bj3R4MJCYAAqnMg.jpg",
  :url=>"http://t.co/Mljw3xOY3B",
  :display_url=>"pic.twitter.com/Mljw3xOY3B",
  :expanded_url=>
   "http://twitter.com/riocampos/status/449746301857447936/photo/1",
  :type=>"photo",
  :sizes=>
   {:medium=>{:w=>600, :h=>537, :resize=>"fit"},
    :small=>{:w=>340, :h=>304, :resize=>"fit"},
    :thumb=>{:w=>150, :h=>150, :resize=>"crop"},
    :large=>{:w=>640, :h=>573, :resize=>"fit"}}},
 {:id=>449746298007076864,
  :id_str=>"449746298007076864",
  :indices=>[118, 140],
  :media_url=>"http://pbs.twimg.com/media/Bj3R4AvCQAA9-Le.jpg",
  :media_url_https=>"https://pbs.twimg.com/media/Bj3R4AvCQAA9-Le.jpg",
  :url=>"http://t.co/Mljw3xOY3B",
  :display_url=>"pic.twitter.com/Mljw3xOY3B",
  :expanded_url=>
   "http://twitter.com/riocampos/status/449746301857447936/photo/1",
  :type=>"photo",
  :sizes=>
   {:medium=>{:w=>599, :h=>1024, :resize=>"fit"},
    :large=>{:w=>599, :h=>1024, :resize=>"fit"},
    :thumb=>{:w=>150, :h=>150, :resize=>"crop"},
    :small=>{:w=>340, :h=>581, :resize=>"fit"}}},
 {:id=>449746298887868416,
  :id_str=>"449746298887868416",
  :indices=>[118, 140],
  :media_url=>"http://pbs.twimg.com/media/Bj3R4EBCEAAUIgg.jpg",
  :media_url_https=>"https://pbs.twimg.com/media/Bj3R4EBCEAAUIgg.jpg",
  :url=>"http://t.co/Mljw3xOY3B",
  :display_url=>"pic.twitter.com/Mljw3xOY3B",
  :expanded_url=>
   "http://twitter.com/riocampos/status/449746301857447936/photo/1",
  :type=>"photo",
  :sizes=>
   {:small=>{:w=>340, :h=>604, :resize=>"fit"},
    :large=>{:w=>576, :h=>1024, :resize=>"fit"},
    :thumb=>{:w=>150, :h=>150, :resize=>"crop"},
    :medium=>{:w=>576, :h=>1024, :resize=>"fit"}}}]

multiphototweet.attrs[:extended_entities][:media].first
=> {:id=>449746301068926976,
 :id_str=>"449746301068926976",
 :indices=>[118, 140],
 :media_url=>"http://pbs.twimg.com/media/Bj3R4MJCYAAqnMg.jpg",
 :media_url_https=>"https://pbs.twimg.com/media/Bj3R4MJCYAAqnMg.jpg",
 :url=>"http://t.co/Mljw3xOY3B",
 :display_url=>"pic.twitter.com/Mljw3xOY3B",
 :expanded_url=>
  "http://twitter.com/riocampos/status/449746301857447936/photo/1",
 :type=>"photo",
 :sizes=>
  {:medium=>{:w=>600, :h=>537, :resize=>"fit"},
   :small=>{:w=>340, :h=>304, :resize=>"fit"},
   :thumb=>{:w=>150, :h=>150, :resize=>"crop"},
   :large=>{:w=>640, :h=>573, :resize=>"fit"}}}

本編

Twitter上の会話をより楽しみやすくするため、写真関連の機能を2つ追加しました。写真に写っている人にタグを付けたり、ツイートに最大4枚の写真を添付できるようになりました。
写真でもっと楽しみませんか

という新機能が加わりましたね。
これをTwitter API的にどう変更されているか確認します。

その１：タグ付け

タグ付けテスト pic.twitter.com/SuCOMQdIWt
— riocampos5 (@riocampos5) March 29, 2014

このツイートをAPIで見てみます。Twitter gem（5.7.1ただし現時点の最新は5.8.0）を使いました。

{:created_at=>"Sat Mar 29 02:58:22 +0000 2014",
 :id=>449742330350682112,
 :id_str=>"449742330350682112",
 :text=>"タグ付けテスト http://t.co/SuCOMQdIWt",
 :source=>
  "<a href=\"http://twitter.com/download/iphone\" rel=\"nofollow\">Twitter for iPhone</a>",
 :truncated=>false,
 :in_reply_to_status_id=>nil,
 :in_reply_to_status_id_str=>nil,
 :in_reply_to_user_id=>nil,
 :in_reply_to_user_id_str=>nil,
 :in_reply_to_screen_name=>nil,
 :user=>
  {:id=>709067502,
   :id_str=>"709067502",
   :name=>"riocampos5",
   :screen_name=>"riocampos5",
   :location=>"",
   :description=>"",
   :url=>nil,
   :entities=>{:description=>{:urls=>[]}},
   :protected=>false,
   :followers_count=>1,
   :friends_count=>1,
   :listed_count=>1,
   :created_at=>"Sat Jul 21 14:32:44 +0000 2012",
   :favourites_count=>0,
   :utc_offset=>nil,
   :time_zone=>nil,
   :geo_enabled=>false,
   :verified=>false,
   :statuses_count=>285,
   :lang=>"ja",
   :contributors_enabled=>false,
   :is_translator=>false,
   :is_translation_enabled=>false,
   :profile_background_color=>"C0DEED",
   :profile_background_image_url=>
    "http://abs.twimg.com/images/themes/theme1/bg.png",
   :profile_background_image_url_https=>
    "https://abs.twimg.com/images/themes/theme1/bg.png",
   :profile_background_tile=>false,
   :profile_image_url=>
    "http://abs.twimg.com/sticky/default_profile_images/default_profile_3_normal.png",
   :profile_image_url_https=>
    "https://abs.twimg.com/sticky/default_profile_images/default_profile_3_normal.png",
   :profile_link_color=>"0084B4",
   :profile_sidebar_border_color=>"C0DEED",
   :profile_sidebar_fill_color=>"DDEEF6",
   :profile_text_color=>"333333",
   :profile_use_background_image=>true,
   :default_profile=>true,
   :default_profile_image=>true,
   :following=>true,
   :follow_request_sent=>false,
   :notifications=>false},
 :geo=>nil,
 :coordinates=>nil,
 :place=>nil,
 :contributors=>nil,
 :retweet_count=>0,
 :favorite_count=>0,
 :entities=>
  {:hashtags=>[],
   :symbols=>[],
   :urls=>[],
   :user_mentions=>[],
   :media=>
    [{:id=>449742329474072576,
      :id_str=>"449742329474072576",
      :indices=>[8, 30],
      :media_url=>"http://pbs.twimg.com/media/Bj3ORAzCQAAjy2i.jpg",
      :media_url_https=>"https://pbs.twimg.com/media/Bj3ORAzCQAAjy2i.jpg",
      :url=>"http://t.co/SuCOMQdIWt",
      :display_url=>"pic.twitter.com/SuCOMQdIWt",
      :expanded_url=>
       "http://twitter.com/riocampos5/status/449742330350682112/photo/1",
      :type=>"photo",
      :sizes=>
       {:large=>{:w=>533, :h=>533, :resize=>"fit"},
        :thumb=>{:w=>150, :h=>150, :resize=>"crop"},
        :medium=>{:w=>533, :h=>533, :resize=>"fit"},
        :small=>{:w=>340, :h=>340, :resize=>"fit"}}}]},
 :favorited=>false,
 :retweeted=>false,
 :possibly_sensitive=>false,
 :lang=>"ja"}

…:mediaのなかに入ってるかと思いましたが入ってませんね。
ではTwitter gemを使わずOAuthを使って直接確認します。
毎度ですが、key/secretはニセモノです。

#!/usr/bin/env ruby
# coding: utf-8
require 'twitter'
require 'oauth'

key_secret = {
  consumer_key:         '9Gu1FiE1IfKi32bR8Fw',
  consumer_secret:      'QUnRDVcl5FNCZ9C1j80OAjUJlguMNVyqbdrOrnjtQ',
  access_token:         '2194235326-sm2SUkVRHMJ1CdwYG1f04klQMlxc4i05tkSbnZa',
  access_token_secret:  'oairK8FMvLZ8dqEVrCgh2brhyL0SCd5wpdkIoNxz62Jdi',
}

# Exchange your oauth_token and oauth_token_secret for an AccessToken instance.
def prepare_access_token(key_secret)
  consumer = OAuth::Consumer.new(
    key_secret[:consumer_key], 
    key_secret[:consumer_secret],
    { 
      site:   "https://api.twitter.com",
      scheme: :header
    }
  )
  # now create the access token object from passed values
  token_hash = { 
    oauth_token:        key_secret[:access_token],
    oauth_token_secret: key_secret[:access_token_secret]
  }
  OAuth::AccessToken.from_hash(consumer, token_hash)
end
 
# Exchange our oauth_token and oauth_token secret for the AccessToken instance.
access_token = prepare_access_token(key_secret)
# use the access token as an agent to get the home timeline
response = access_token.request(:get, "https://api.twitter.com/1.1/statuses/user_timeline.json?screen_name=riocampos5&count=1")

これをpryで実行して、返ってきたのがこちら。

pry(main)> pp JSON.parse(response.body);
[{"created_at"=>"Sat Mar 29 02:58:22 +0000 2014",
  "id"=>449742330350682112,
  "id_str"=>"449742330350682112",
  "text"=>"タグ付けテスト http://t.co/SuCOMQdIWt",
  "source"=>
   "<a href=\"http://twitter.com/download/iphone\" rel=\"nofollow\">Twitter for iPhone</a>",
  "truncated"=>false,
  "in_reply_to_status_id"=>nil,
  "in_reply_to_status_id_str"=>nil,
  "in_reply_to_user_id"=>nil,
  "in_reply_to_user_id_str"=>nil,
  "in_reply_to_screen_name"=>nil,
  "user"=>
   {"id"=>709067502,
    "id_str"=>"709067502",
    "name"=>"riocampos5",
    "screen_name"=>"riocampos5",
    "location"=>"",
    "description"=>"",
    "url"=>nil,
    "entities"=>{"description"=>{"urls"=>[]}},
    "protected"=>false,
    "followers_count"=>1,
    "friends_count"=>1,
    "listed_count"=>1,
    "created_at"=>"Sat Jul 21 14:32:44 +0000 2012",
    "favourites_count"=>0,
    "utc_offset"=>nil,
    "time_zone"=>nil,
    "geo_enabled"=>false,
    "verified"=>false,
    "statuses_count"=>285,
    "lang"=>"ja",
    "contributors_enabled"=>false,
    "is_translator"=>false,
    "is_translation_enabled"=>false,
    "profile_background_color"=>"C0DEED",
    "profile_background_image_url"=>
     "http://abs.twimg.com/images/themes/theme1/bg.png",
    "profile_background_image_url_https"=>
     "https://abs.twimg.com/images/themes/theme1/bg.png",
    "profile_background_tile"=>false,
    "profile_image_url"=>
     "http://abs.twimg.com/sticky/default_profile_images/default_profile_3_normal.png",
    "profile_image_url_https"=>
     "https://abs.twimg.com/sticky/default_profile_images/default_profile_3_normal.png",
    "profile_link_color"=>"0084B4",
    "profile_sidebar_border_color"=>"C0DEED",
    "profile_sidebar_fill_color"=>"DDEEF6",
    "profile_text_color"=>"333333",
    "profile_use_background_image"=>true,
    "default_profile"=>true,
    "default_profile_image"=>true,
    "following"=>true,
    "follow_request_sent"=>false,
    "notifications"=>false},
  "geo"=>nil,
  "coordinates"=>nil,
  "place"=>nil,
  "contributors"=>nil,
  "retweet_count"=>0,
  "favorite_count"=>0,
  "entities"=>
   {"hashtags"=>[],
    "symbols"=>[],
    "urls"=>[],
    "user_mentions"=>[],
    "media"=>
     [{"id"=>449742329474072576,
       "id_str"=>"449742329474072576",
       "indices"=>[8, 30],
       "media_url"=>"http://pbs.twimg.com/media/Bj3ORAzCQAAjy2i.jpg",
       "media_url_https"=>"https://pbs.twimg.com/media/Bj3ORAzCQAAjy2i.jpg",
       "url"=>"http://t.co/SuCOMQdIWt",
       "display_url"=>"pic.twitter.com/SuCOMQdIWt",
       "expanded_url"=>
        "http://twitter.com/riocampos5/status/449742330350682112/photo/1",
       "type"=>"photo",
       "sizes"=>
        {"large"=>{"w"=>533, "h"=>533, "resize"=>"fit"},
         "thumb"=>{"w"=>150, "h"=>150, "resize"=>"crop"},
         "medium"=>{"w"=>533, "h"=>533, "resize"=>"fit"},
         "small"=>{"w"=>340, "h"=>340, "resize"=>"fit"}}}]},
  "favorited"=>false,
  "retweeted"=>false,
  "possibly_sensitive"=>false,
  "lang"=>"ja"}]

…Twitter gemでの返値と全く一緒です。
結局、APIでのアクセスでは、写真のタグ付け情報が含まれていませんでしたorz

その２：写真複数添付

タグ付けされた側は通知が来る。そしてタグ付けを含むツイートには（ツイートした垢が鍵付きじゃなければ、タグ付けに関係しない垢からも）タグ付けされた垢名を確認できる。新機能の写真タグ付けに加え、写真は1ツイート4枚まで追加可能になった。 pic.twitter.com/Mljw3xOY3B
— riocampos（りおかんぽす） (@riocampos) March 29, 2014

{:created_at=>"Sat Mar 29 03:14:08 +0000 2014",
 :id=>449746301857447936,
 :id_str=>"449746301857447936",
 :text=>
  "タグ付けされた側は通知が来る。そしてタグ付けを含むツイートには（ツイートした垢が鍵付きじゃなければ、タグ付けに関係しない垢からも）タグ付けされた垢名を確認できる。\n新機能の写真タグ付けに加え、写真は1ツイート4枚まで追加可能になった。 http://t.co/Mljw3xOY3B",
 :source=>
  "<a href=\"http://twitter.com/download/iphone\" rel=\"nofollow\">Twitter for iPhone</a>",
 :truncated=>false,
 :in_reply_to_status_id=>nil,
 :in_reply_to_status_id_str=>nil,
 :in_reply_to_user_id=>nil,
 :in_reply_to_user_id_str=>nil,
 :in_reply_to_screen_name=>nil,
 :user=>
  {:id=>56997313,
   :id_str=>"56997313",
   :name=>"riocampos（りおかんぽす）",
   :screen_name=>"riocampos",
   :location=>"Osaka, Japan",
   :description=>
    "plz call me rio☆ favorite: cycle road race & figure skate, Mac!, iPhone!, Ruby, Fine-Art, Science, Black/Green Tea. | Gender:♂ facebook: http://t.co/uP8O6PBYoU",
   :url=>"http://t.co/5yB3nIR3VQ",
   :entities=>
    {:url=>
      {:urls=>
        [{:url=>"http://t.co/5yB3nIR3VQ",
          :expanded_url=>"http://about.me/riocampos",
          :display_url=>"about.me/riocampos",
          :indices=>[0, 22]}]},
     :description=>
      {:urls=>
        [{:url=>"http://t.co/uP8O6PBYoU",
          :expanded_url=>"http://on.fb.me/MvEV7P",
          :display_url=>"on.fb.me/MvEV7P",
          :indices=>[137, 159]}]}},
   :protected=>false,
   :followers_count=>2100,
   :friends_count=>2304,
   :listed_count=>192,
   :created_at=>"Wed Jul 15 12:02:35 +0000 2009",
   :favourites_count=>2906,
   :utc_offset=>32400,
   :time_zone=>"Osaka",
   :geo_enabled=>true,
   :verified=>false,
   :statuses_count=>166384,
   :lang=>"en",
   :contributors_enabled=>false,
   :is_translator=>false,
   :is_translation_enabled=>false,
   :profile_background_color=>"48E0B7",
   :profile_background_image_url=>
    "http://pbs.twimg.com/profile_background_images/378800000158576090/WjPzbAXY.jpeg",
   :profile_background_image_url_https=>
    "https://pbs.twimg.com/profile_background_images/378800000158576090/WjPzbAXY.jpeg",
   :profile_background_tile=>true,
   :profile_image_url=>
    "http://pbs.twimg.com/profile_images/3462273402/f331afb1b57c7d39688229e86de95881_normal.jpeg",
   :profile_image_url_https=>
    "https://pbs.twimg.com/profile_images/3462273402/f331afb1b57c7d39688229e86de95881_normal.jpeg",
   :profile_banner_url=>
    "https://pbs.twimg.com/profile_banners/56997313/1365179721",
   :profile_link_color=>"009999",
   :profile_sidebar_border_color=>"FFFFFF",
   :profile_sidebar_fill_color=>"EFEFEF",
   :profile_text_color=>"333333",
   :profile_use_background_image=>true,
   :default_profile=>false,
   :default_profile_image=>false,
   :following=>false,
   :follow_request_sent=>false,
   :notifications=>false},
 :geo=>nil,
 :coordinates=>nil,
 :place=>nil,
 :contributors=>nil,
 :retweet_count=>0,
 :favorite_count=>1,
 :entities=>
  {:hashtags=>[],
   :symbols=>[],
   :urls=>[],
   :user_mentions=>[],
   :media=>
    [{:id=>449746301068926976,
      :id_str=>"449746301068926976",
      :indices=>[118, 140],
      :media_url=>"http://pbs.twimg.com/media/Bj3R4MJCYAAqnMg.jpg",
      :media_url_https=>"https://pbs.twimg.com/media/Bj3R4MJCYAAqnMg.jpg",
      :url=>"http://t.co/Mljw3xOY3B",
      :display_url=>"pic.twitter.com/Mljw3xOY3B",
      :expanded_url=>
       "http://twitter.com/riocampos/status/449746301857447936/photo/1",
      :type=>"photo",
      :sizes=>
       {:medium=>{:w=>599, :h=>537, :resize=>"fit"},
        :thumb=>{:w=>150, :h=>150, :resize=>"crop"},
        :large=>{:w=>640, :h=>573, :resize=>"fit"},
        :small=>{:w=>339, :h=>304, :resize=>"fit"}}}]},
 :favorited=>false,
 :retweeted=>false,
 :possibly_sensitive=>false,
 :lang=>"ja"}

…これも写真へのURL http://pbs.twimg.com/media/Bj3R4MJCYAAqnMg.jpg が1枚目にしか張られていない。
念のためOAuthでもみてみましょうか。

pp JSON.parse(response.body);
{"created_at"=>"Sat Mar 29 03:14:08 +0000 2014",
 "id"=>449746301857447936,
 "id_str"=>"449746301857447936",
 "text"=>
  "タグ付けされた側は通知が来る。そしてタグ付けを含むツイートには（ツイートした垢が鍵付きじゃなければ、タグ付けに関係しない垢からも）タグ付けされた垢名を確認できる。\n新機能の写真タグ付けに加え、写真は1ツイート4枚まで追加可能になった。 http://t.co/Mljw3xOY3B",
 "source"=>
  "<a href=\"http://twitter.com/download/iphone\" rel=\"nofollow\">Twitter for iPhone</a>",
 "truncated"=>false,
 "in_reply_to_status_id"=>nil,
 "in_reply_to_status_id_str"=>nil,
 "in_reply_to_user_id"=>nil,
 "in_reply_to_user_id_str"=>nil,
 "in_reply_to_screen_name"=>nil,
 "user"=>
  {"id"=>56997313,
   "id_str"=>"56997313",
   "name"=>"riocampos（りおかんぽす）",
   "screen_name"=>"riocampos",
   "location"=>"Osaka, Japan",
   "description"=>
    "plz call me rio☆ favorite: cycle road race & figure skate, Mac!, iPhone!, Ruby, Fine-Art, Science, Black/Green Tea. | Gender:♂ facebook: http://t.co/uP8O6PBYoU",
   "url"=>"http://t.co/5yB3nIR3VQ",
   "entities"=>
    {"url"=>
      {"urls"=>
        [{"url"=>"http://t.co/5yB3nIR3VQ",
          "expanded_url"=>"http://about.me/riocampos",
          "display_url"=>"about.me/riocampos",
          "indices"=>[0, 22]}]},
     "description"=>
      {"urls"=>
        [{"url"=>"http://t.co/uP8O6PBYoU",
          "expanded_url"=>"http://on.fb.me/MvEV7P",
          "display_url"=>"on.fb.me/MvEV7P",
          "indices"=>[137, 159]}]}},
   "protected"=>false,
   "followers_count"=>2100,
   "friends_count"=>2304,
   "listed_count"=>192,
   "created_at"=>"Wed Jul 15 12:02:35 +0000 2009",
   "favourites_count"=>2906,
   "utc_offset"=>32400,
   "time_zone"=>"Osaka",
   "geo_enabled"=>true,
   "verified"=>false,
   "statuses_count"=>166389,
   "lang"=>"en",
   "contributors_enabled"=>false,
   "is_translator"=>false,
   "is_translation_enabled"=>false,
   "profile_background_color"=>"48E0B7",
   "profile_background_image_url"=>
    "http://pbs.twimg.com/profile_background_images/378800000158576090/WjPzbAXY.jpeg",
   "profile_background_image_url_https"=>
    "https://pbs.twimg.com/profile_background_images/378800000158576090/WjPzbAXY.jpeg",
   "profile_background_tile"=>true,
   "profile_image_url"=>
    "http://pbs.twimg.com/profile_images/3462273402/f331afb1b57c7d39688229e86de95881_normal.jpeg",
   "profile_image_url_https"=>
    "https://pbs.twimg.com/profile_images/3462273402/f331afb1b57c7d39688229e86de95881_normal.jpeg",
   "profile_banner_url"=>
    "https://pbs.twimg.com/profile_banners/56997313/1365179721",
   "profile_link_color"=>"009999",
   "profile_sidebar_border_color"=>"FFFFFF",
   "profile_sidebar_fill_color"=>"EFEFEF",
   "profile_text_color"=>"333333",
   "profile_use_background_image"=>true,
   "default_profile"=>false,
   "default_profile_image"=>false,
   "following"=>false,
   "follow_request_sent"=>false,
   "notifications"=>false},
 "geo"=>nil,
 "coordinates"=>nil,
 "place"=>nil,
 "contributors"=>nil,
 "retweet_count"=>0,
 "favorite_count"=>1,
 "entities"=>
  {"hashtags"=>[],
   "symbols"=>[],
   "urls"=>[],
   "user_mentions"=>[],
   "media"=>
    [{"id"=>449746301068926976,
      "id_str"=>"449746301068926976",
      "indices"=>[118, 140],
      "media_url"=>"http://pbs.twimg.com/media/Bj3R4MJCYAAqnMg.jpg",
      "media_url_https"=>"https://pbs.twimg.com/media/Bj3R4MJCYAAqnMg.jpg",
      "url"=>"http://t.co/Mljw3xOY3B",
      "display_url"=>"pic.twitter.com/Mljw3xOY3B",
      "expanded_url"=>
       "http://twitter.com/riocampos/status/449746301857447936/photo/1",
      "type"=>"photo",
      "sizes"=>
       {"medium"=>{"w"=>599, "h"=>537, "resize"=>"fit"},
        "thumb"=>{"w"=>150, "h"=>150, "resize"=>"crop"},
        "large"=>{"w"=>640, "h"=>573, "resize"=>"fit"},
        "small"=>{"w"=>339, "h"=>304, "resize"=>"fit"}}}]},
 "favorited"=>false,
 "retweeted"=>false,
 "possibly_sensitive"=>false,
 "lang"=>"ja"}

…やっぱ同じか。
~~API拡張してほしいなぁ。~~

*1:シンボルをキーにしている点だけ異なるが、たしかJSONライブラリでオプション指定することでキーをシンボル化できたと思う