Guessing I'll have to wait for the modders to take hold of this now that the SDK has been released cause sure seems like Sammy is taking their sweet sweet time with this tease.
....Update: At this time it only let's you share an image with the FB QuickView App. Being that I really don't use FaceBook, it's still kinda useless.
Update: The FB QuickView App is garbage when it comes to the share feature. Tested it and the app just hangs and loops while hoping to get the share thing to work.