This is a pretty big update - but it focuses mainly on the Admin area. You can see a nice video over at my blog and download the bits from RIAForge.org.
Read the readme.txt for details, but here are the high level changes:
Removed Spry and Tabber. jQuery+jQuery UI used.
Body text area auto grows as you type.
Related Entries improved to support blogs with lots of entries.
Admin now checks for a new version. Helps you detect if your blog is out of date.
If you go to the next page on the blog, you now have a previous entries link to go backwards.
SweetTweets/ColdFish updated to latest version.