The new playlist bar: Introduced first last week and received some bad response from the community. In particular, most people did not like the autoplay feature.
They're still keeping the play bar but have changed it from being on autoplay by default.
The new revamped music page was released recently and today a new "Events Near You" feature is added which is pretty cool.
Annotation Revamp: Annotations have gotten a new look, and can now be transparent with just text, and some other things. Though the feature where you can see who added an annotation seems to be (bugging?) not working.
Video With Open Annotations:
Embedddable Badges: A bunch of new badges to put on your blog or site are now available from the creators corner
Some other new features that were added with this update:
Buzz on your homepage, now you can see your google buzz friend's videos on your Youtube homepage
Free previews of video rentals
the new HTML 5 embedding system and some changes to your "My Videos" page.