There were a couple of articles about Blogger Beta at Digg and ZDNet on 8/14 and of course, I had to check it out. I couldn't switch over to beta immediately, so I had to create a new account. That's easy because Blogger Beta is linked to Google Accounts as well, so if you have a GMail account, you won't need a different password.
The new features include:
Layouts (drag and drop function to change the layout of the page)
More Feeds (including RSS)
Dynamic serving (no more republishing!)
Access control (only registered members can read the blog)
Take the tour to find out more info.