For The First Time Ever, iPhone Owner Loyalty Declines
Could just be that people are finding the older phones work just as well. Some might not like the interface changes.
Then there's this:
New wireless pricing: more data, bigger bill - SFGate
I've seen articles that seem to prove Apple users use more data. Maybe they are wising up to the fact that all this convenience needs to be paid for.
TMO - Average user - less that 1G, Galaxy 3S 1.8G