Facebook's fistfuls of cash come almost exclusively from advertising, but virtually none of it comes from mobile. Much to its delight and our chagrin, that's changing. Prospective advertisers now only need to use the social network's ready-made ad interface and Power Editor to back a sponsored news feed story on mobile devices, instead of getting the explicit say-so from Facebook. It's not open season on Facebook's mobile apps: we won't see dating ads rear their pretty heads in Facebook Camera anytime soon. All the same, it d