BuddyPress.org

I haven’t tried deep integration with forums on a subdomain yet, so I can’t promise you a solution right away, but I would imagine it shouldn’t matter where your forums are, just as long as it’s including the file correctly.

I’ll give this type of setup a try and see what I come up with.

One question though… Are you using a wildcard subdomain setup, or do you simply wave wpmu setup in a subdomain?