You will like this one :
<a href="http://arstechnica.com/apple/news/2010/01/apple-responsible-for-994-of-mobile-app-sales-in-2009.ars" rel="nofollow">http://arstechnica.com/apple/news/2010/01/apple-responsible-...</a>
I stumbled upon it here on YC, so just stay tuned here, there's almost daily a post about iphone app store economics.