http://i.imgur.com/c5pHt.png
I would love to see that compared to users. Especially if new users flattened out somewhat compared to increasing revenues.
I am not sure, but I dont think that FB userbase went up by 4.5x in the same period as did revenues.
That means they are getting far better at monetizing the users/advertisers are willing to spend far more to advert to the users, than before.