That's *very* interesting, although the problem I have with Facebook isn't the data being intercepted but with Facebook itself. Not enough benefit provided for the information and privacy it costs me. Still, it's a step.
It's unexpected move but perhaps it's to show Facebook are serious about your trust. I added my key because I think increasing usage of PGP can only be a good thing. I would love if we can shake the myth that encryption is only used by terrorists and paedophiles.