Eliot Van Buskirk:
Apple/Quattro has unique access to iTunes store data.If a developers choose Apple’s advertising platform over a competing platform, they can more easily track the percentage of impressions led to users clicking through to the iTunes store and purchasing the full version of an app — a statistic commonly referred to as a conversion ratio.
This has all sorts of stink on it. I think the only way Apple gets in trouble for this is if iAds is a run away hit. Otherwise it is of little consequence.