You're mostly right. There is a lot more sophistication now, but most of the advances facebook has made are in two areas:

-Mobile. Making messaging a central strength of the platform. Figuring this out is a big piece of why the stock is doing so well. -Conversations. Facebook has become the default place for people to discuss (or, more accurately, shout about) media/news. I mean both news from external sources and personal life events.

Everything else is reorganizations of existing features in new ways, like the shift from the wall to the timeline. It was a new feature that better fit an existing goal, not an expansion in the scope of the service.