On the popular iPhone app.
Just the day before, President Barack Obama had signed on and begun sending out photos. This seemed like a real sign that Instagram had arrived. Obama already has accounts on Flickr and Facebook. He (or his people) must have seen something unique and wonderful in Instagram's audience, some way to reach people via that channel that it couldn't through others. When the President joins your network, it's news. And while it's great news, it can be the kind of thing a company isn't prepared for. But as it turns out, Obama is a fractional compared to Justin Bieber.