Essentially, they're changing YouTube from a video site to a WWW video platform. The new APIs allow developers to:

* Upload videos and video responses to YouTube

* Add/Edit user and video metadata (titles, descriptions, ratings, comments, favorites, contacts, etc)

* Fetch localized standard feeds (most viewed, top rated, etc.) for 18 international locales

* Perform custom queries optimized for 18 international locales

* Customize player UI and control video playback (pause, play, stop, etc.) through software

Hopefully, I'll be posting a case study from our site within the next couple weeks.