Like Twitter, Facebook is good for sending out fast, brief bulletins to one's list of friends. But also like Twitter, the posts aren't archived in an organized or searchable form. I believe they scroll off the site completely after a short period of time, which is not helpful when someone has put a lot of research into something. It's too ephemeral.
Add to that the fact many won't join Facebook, or are thinking of leaving it, due to Facebook constantly compromising their privacy policy, or changing it without warning. It may be the hub of social networking right now, but it may well crash and burn as fast as it rose, taking all our data with it.
I think that if people want to send out notices in links and status updates on Facebook or Twitter, they can always link to the more substantial, and more permanent, discussions here. Many people do this already. But other than that I don't see it as a productive use of our time to try to maintain two boards on the same topics, and certainly not on as buggy a site as Facebook.
