YouTube is the latest service to join the GData family. Now you can search through YouTube's index and get detailed video, user, and playlist information in the form of GData feeds. If you haven't built something with YouTube yet, now's a great time to get started! Here are some examples to give you ideas.
Search through the index for new 'puppies' videos (I subscribe to this query, doesn't everyone?): http://gdata.youtube.com/feeds/videos?vq=puppies&orderby=updated
For the old-school YouTube developers, the migration guide has info on switching over, including the upgrade timeline (you'll have at least a year). Head over to the YouTube API Announcement Blog for the rest of the details.
I'm looking forward to seeing new faces in our developer forum - feel free to stop by with questions or feedback.