I'm sure we'll compile a list of new features.
In the meantime, you can get an idea by looking at some of the check-in notes on the Source Code tab. All check-ins after 4/13/2009 have been for the latest codebase of BE which will become the next version.
Probably the two most notable new features are the new comment moderation system and multiple widget zones. Lots of other bug fixes and improvements too.