bbPress.org

I have already tested the integration of WP 2.7.1 and bbPress 0.9.0.5 here : http://blog.ashfame.com/2009/05/integrate-bbpress-forum-with-your-wordpress-setup/

Although WordPress 2.8 should work fine (theoretically) by following that integration tutorial but I havn’t tried it yet. I will let you know if I face any issue and will update the tutorial.

Hope that helps!