I don't understand this focus on average revenues. With few exceptions, most of the iPhone developers I personally know make their money by consulting for companies on their free apps.

They have apps on the app store, sometimes for personal gratification only. For instance, one guy does tab bar-type content/search apps for most of his income, and he laments that he can't get paid to make games (his true love - and he has two games on the app store. One of them, a card game, has done quite well). Yes, he still carves out a small slice for personal fulfillment game projects.