The source code for Facebook Competitor Diaspora is out, pre-alpha state, but out and available. Thing is I'm not sure how much this is still needed. Facebook solved (well, in theory) a lot of the security issues that had this project starting in the first place, and while I 100% agree that an alternative is needed, FB no longer being (as) evil means that it's going to be that much harder for Diaspora (which needs a better name) to gain traction.

Here's the developer blog post on the Diaspora site.