From our previous post

We have successfully upgraded our wordpressmu from 2.9.2 to 3.0.1

Here are the steps we followed for this upgradation

http://wpmu.org/how-to-upgrade-wpmu-2-9-2-to-wordpress-3-0-in-5-easy-steps/

We have also upgraded all our plugins and we are happy to say that we are in WordPress-3 club.

Have fun!!