This is a pretty big feature for Blogger: Custom Domains with hosting on Blogspot. Blogger has always allowed you to have your own domain, via FTP publishing. (And for a while, there was a way to get your own domain via "Blog*Spot Plus.") But now that the new version of Blogger does dynamic publishing, there are features you get when you host on Blogspot that you don't get if you FTP (e.g., such as dynamic template modules and access controls). But now you can get them and have your own domain.
Unfortunately, there's not yet built-in domain purchasing/management (even though Google is a registrar and they have that for Google Apps for your Domain. That would make it easier for usersand be a nice little business for them. (Yes, always concerned about revenues at the big G.) But that's undoubtedly on the radar.
I'll switch as soon as I figure out what to do with my stupid .asp extensions. (I haven't used ASP on this site for many years, but I started publishing that way, and now since there are thousands of pointers to those URLs, it's hard to get off of it.)