According to this blog post it seems that Instagram - the photo sharing iPhone app - has reached a million users. Congrats to them! It's a great, simple, app worthy of a huge user base. In fact, it's kind of what I'd expect from a Flickr app in terms of photos coming in via a feed - instead of just a way to view collections. Highly recommended if you're into taking random photos of things and putting pre-made filters on them (as I am).