So the rumor of a Facebook phone has finally come to a head. It seems the Facebook phone isn't really a phone it is more about apps. In this case, the product is Facebook Home. Facebook Home aims to take over parts of your android phone with Facebook content. Think Facebook chat instead of text messaging, or Facebook camera instead of your typical camera. Long story short, Facebook wants to take over your mobile phone.
You will be able to double tap to like something and can swipe from one update to the next. Tap to comment, tap and hold to zoom, etc, I think this makes sense for folks whose social lives exist mainly on Facebook, for the rest of the people who use their phone for other things, not so much.