Twitter Tests Expandable Timeline

Twitter is testing an expandable timeline under the radar so that all media related information can be seen inside the timeline rather than off to the side or when clicking on another page. The new timeline, originally reported by Patrick Bisch of Pinglio, will allow users to click on other tweets in order to expand conversations, viewing the entire thread, retweets and other media such as videos and photos. It allows for easier and faster navigation and activity.
While Twitter has not yet formerly commented on the re-design, some users have already reported seeing the new timeline on the site.
The screen shot below is an example of how users can expand a conversation and see other users who have retweeted or commented on the original post:

 source: cnet