They were hacked. There are a lot of people who use phones outside of AT&T, and the European carriers. But, are 1/3 of Apple's iPhones hacked? Probably.
For the people who say that they are in the "channel", we have to wonder what they are referring to. RoughlyDrafted points this out as well. iPhones are only sold by Apple's online store and retail and its telecom partners. Not by Best Buy or Target or Circuit City. Apple knows exactly what's in its inventory. It also knows what AT&T and the EU'