Cool article Amy. I think it's kind of similar to what Tumblr did and even Twitter for that matter. Like you said, the key is for the advertisement to blend in so you really can't tell the difference between an advertisement or a user posted picture. A really good point I read somewhere was something like " why would any brand pay Instagram to advertise when they already can for FREE ? ". If an advertisement is just a picture that looks like any other Instagram post, why not just start a FREE Instagram account and post pictures of your stuff that way ? Just some food for thought.