Open source is very good at some things, and not so good at others. For example, if Facebook wants to open source its application platform to make it easier to create and integrate applications into the Facebook platform, open source is good at that. Just look at Mozilla's Firefox or Drupal.
But is this Facebook's biggest problem? Ben Lorica hints at a bigger underlying problem that no code license can solve:
Actually, the more probable scenario is that (closed) social networks become less important over the long term. With more web applications incorporating social features, users will gradually "leave" closed social networks altogether. Already, I know less and less people who use Facebook regularly. Most people I know log in only when they receive a "friend" request - sadly hugs, gifts, zombies and pokes are losing their allure.
The primary problem with Facebook is not applications. The primary problem with Facebook is utility. When was the last time that Facebook enabled much of anything useful in your life?
It does happen, but not as often as it should. Dave Rosenberg and I spent some time the other day looking up old friends. I found someone from my fourth grade class in Virginia on Facebook on Friday. I had no idea what to do with that information, but there it was.
I use LinkedIn for recruiting. It provides tangible business value that I can expense. I've tried to use Facebook but it's such a bundle of obnoxious noise that I have no idea what to do with it. I've said before that, and then monetize it, but it's going to have to abandon its "friendly" promiscuity first.
Open source is not going to save Facebook from itself. It may well turn the social networking space into a "race to openness," as Glyn suggests. This will be good.
It might make Facebook a more relevant development platform, but it's not going to resolve Facebook's core business problem, which is that today it offers precious little business value, by which I mean that its consumer data/interactions are too dirty and too random to yield substantive value that advertisers and others will pay to access.