I've added a post-script to this story, updating with developments over the last year:
http://petewarden.typepad.com/searchbrowser/2011/03/facebook...
In particular, I know from my friends in the academic community that they're quietly putting together processes for working with researchers. That's a big step forward in my view, as long as they can safeguard privacy, there's a lot of potential for world-improving research.