Oh look. What do we have here? In exploring Facebook's redesign, I spied a new tab under "Account," called "Credits Balance." When you click on it, it opens this:
So here we can guess that soon you'll be paying for all of that virtual clutter people are sending (That's YOU, farmers) and those endless games of free Bejeweled could be coming to an end. But bigger news, if my theory is true, is that Facebook has finally found themselves a micro-purchasing revenue model (which includes buying social ads and likely more to come) and quietly rolled it out buried in a redesign.
Congratulations, Facebook. You just may be all growz up. Your parents, also known as investors, will be so proud. And rich.