bbPress.org

This did not work for me. In fact, it was the thing that hindered my integration from working properly. That is just my experience, though.

Following these instructions:

http://bavatuesdays.com/integrating-wpmu-buddypress-and-bbpress/

I finally have WPMU-bbPress integration working.

There are several tips and an additional plugin mentioned there that are essential with WPMU integration.

Sam’s screencast helped with everything else.