IEBlog lists all the changes, bug fixes, CSS fixes/additions in Internet Explorer 7. This looks to be a new era for Microsoft when it comes to standards compliance. Well, at least a stepping stone in the right direction.
I have been using beta 3 of IE7 on my laptop, and yes, it is way better than IE6, although there are still some minor quirks and the occasional crash. But when it comes to CSS (and transparent PNG support) it is leaps ahead.