And I have to wonder how many of those users will come to regret that they shot all their babby-pictures in some deliberately cruddy format instead of the best possible available to them.
That's impressive growth! They've carved out a niche for mobile photo sharing with their iPhone app. Now they're letting developers extend on the web via the API.<p>People usually talk about viral growth on Facebook, but Instagram has recreated it on the iPhone platform. And they haven't even released their Android version yet!