It’s not so much about the phone and new, amazing technology, it’s more about making an international push, to get more people to use their phones (and of course facebook, that will jump out of your phone :) ). The more people they will get to use it on their phones, the more ads they can deliver ;)
What sort of demand are they expecting for this? The only people I can imagine that would want a facebook phone are primarily teenage girls. A lucrative demographic, I suppose. It just seems like a mismatch for the company.