The usual backlash kicks in: some vocal Facebook critics don’t love that it’s buying Instagram, even though the product will almost certainly survive (and thrive). Om says Facebook made such an uncharacteristically big acquisition because Instagram was a legitimate threat to Facebook with mobile DNA. And a passionate community. I suspect there’s a pretty high overlap between Instagram’s 30 million users and Facebook’s 850 million, and, from a competitive perspective, Instagram might be worth even more to companies like Google or Apple who lack that social gene. Observers point out Instagram is a natural for location data – another Facebook near-failure – and may have some role in getting Facebook into China. That last one’s a stretch. Does this put other mobile photo services in play? None have that magic combination of size (Flickr) and mobile growth. And I’d rate Pinterest’s prospects much higher than Path’s. Unlike Path, Pinterest has actual audience growth, user loyalty, and a fairly obvious set of monetization options.