WTF?

Instagram is worth $1 billion, really?
It was valued at $500 million last month and it took an offer of 1 billion to snatch it away from its owners.
They have 50 million users right now, but are expecting another 50 million now that the service is on Android.
How the heck can a picture app get 100 million users? That's insane! They have $0 revenues by the way, yet Facebook bought them for $1 billion... shocking!