WordPress MU

I have a single user WP site which is a basic blog. I have more contributors coming on board and was having a look at MU to make it a better experience.

Can I have it so that people can sign up for an account, they have a profile etc and can connect to other users (I have looked at BuddyPress) and the blog articles just appear on the homepage under certain categories that I set out?

Many thanks

BuddyPress can now run on single WP ,if you use the trunk version.

If you want to use MU for multiple blogs, you have to *replace* your current WP install.

If you don't want to do that, wait for 3.0. When you upgrade to that, you can turn on multiple blogs.