Here's what I wrote about it a few months ago:

"iOS development by the numbers
Steve Jobs is trying to convince folks that developing for the iOS ecosystem (iOS is the new name for the OS that runs iPhone, iPod Touch, and iPad) is a financial winner. His numbers, though, only appeal to those who are mathematically challenged. He claims $1 billion has been paid to app developers, and he says that there are 250,000 apps out there. That comes out to a paltry $4,000 per app. Sounds like a lot? Not exactly. Four grand is decent money if you spend a few nights and weekends on it, or if you are monetizing a labor of love. It certainly isn?t ?quit my day job money? even if the ?day job? is flipping burgers. They are about to sell the 100 millionth device. That means that each iOS device generates a ?whopping? $10 for app developers. Wee. Who cares how many iOS users have their credit cards stored and ready to spend, when they are spending a mere $10 on apps per device? Oh, and the $60 million in ad inventory doesn?t look so impressive when you realize that it is less than $1 per device. Jobs? numbers may impress some of the so-called ?analysts? out there, but I can do enough basic math to know better."