Something fell into place for me when I read this interview. Like when Google bought YouTube, it took me a while to realize that Google would own internet video. Facebook is sitting on a huge pile of social data. With social graphs and tagged faces the more obvious ones, they also have a huge corpus of natural language and personal likes. With this one could create AI that is much more down to earth and friendly to communicate with. It may posses a form of emotional intelligence. It may have knowledge on social interactions, status, moods, human relationships etc. it knows what makes us tick.
Contrast with Google which basically indexed the entire internet. I expect an advanced future interaction with Google AI to be more factual. The kid you want to do your homework for you, not the kid you hang out with later, who suggests new Jazz songs for you to listen to when it starts to rain outside.