It's been (just over) one year and I haven't heard anything about Diaspora in...well, a while. Jan 31 was the last blog post on their site -- has anyone heard aything outta them from some other news source?
Their Github is certainly active still...but it only looks like only two of the "original authors" have committed to it recently.
A primary problem I see with that approach would have been deciding which to use in the first place, which may have been seen as taking a 'kingmaker' attitude towards existing projects ("we're gonna bless you with a lot of money and attention") (though that's probably reading a bit more in to it than it merits).
Also, the decision process would have required a lot of code review of existing projects to determine which ones were solid (well-architected, easy to modify, well-documented, secure, etc). to begin with. This takes a lot of time and effort, though a submissions process or contest could have been set up to help make that more efficient.
Possibly going further, developing a federation model alone, then using the money to work with a variety of the top open source social network projects to integrate in to the newly developed model would have been a possibly stronger approach. They're not limiting things to one project, and the value is more quickly spread around to a multitude of projects, and therefore users, regardless of platform. Not everyone likes or uses Rails, or PHP, or .Net, or Python, or whatever), but everyone can use RSS, OAuth and other common standards.
Diaspora had a chance to have a huge impact on the social networking scene, and blew it. Obviously that's from my perspective. They still have the opp of putting out a nice Rails-based social network, but I don't think (given the current state and pace) it'll ever be much more than that.