The FreeGameDev community has a section for projects looking for collaborators and developers: http://forum.freegamedev.net/viewforum.php?f=22

There is also the FreeGameDev wiki with more information on getting involved with open source / Free software game development.

The advantage that FreeGameDev community has over GameDev etc is that is it specifically for open source / Free software games.

The FreeGameDev community originated from the Free Gamer blog, which is a blog tracking Free software game news.