[jlgbecom]

There's a ton of them, and they're all pretty mature. I'm hoping this does have a windfall effect on the ones that have already proven themselves from a code standpoint, and could use the hype that Diaspora has

http://opensource.appleseedproject.org

http://www.onesocialweb.org

http://www.gnu.org/software/social

http://www.elgg.org