bbPress is finally moving towards 1.0, and it looks like it may get there quickly. The tutorial that I wrote up about integrating WPMU, BuddyPress, and bbPress was actually for bbPress Alpha, so I took the time to update today. The cookie integration details changed slightly for me for WPMu 2.7.1, so I figured I would update the tutorial. Particularly because it has gotten almost 10,000 views in six months, something that reminds me that people read the bava for WPMu How-Tos far more than my navel gazing film and theory posts—though I would argue the latter are far superior
Anyway, below is a link to the updated tutorial, if you are still working with the Alpha I recommend you update because RC3 seems pretty stable and the cookie integration is almost there, which will make this tutorial obsolete so very soon.
Link to tutorial for Integrating WPMu, BuddyPress, and bbPress updated for bbPress 1.0-rc3