BuddyPress.org

In addition to what DJPaul said, BuddyPress no longer requires itself to be activated site wide. You can pick and choose which blogs BuddyPress is loaded on in each specific blogs' plugins screen.

When I activate bp on one site, it shows up in the plugins folder as activated site wide. I do not see an option of only activating it on a given blog.

I am running wpmu2.9.1 and bp 1.2beta using subdomains install.

I have also set bp root blog to all sites…. maybe that is the problem?