Actually it happens quite often. If you buy any electronics at say, Best Buy, and the price is lowered within 30 days, you can get the price adjusted. I'm pretty sure this generally ends up going back to the manufacturers in the case of a manufacturer price cut. If you had been able to buy your iPhone at Best Buy, you would have been able to get a $200 refund instead of just a $100 store credit. Apple is really doing less than the competition here.

It's nothing they have to do, but they're hardly going above and beyond when the largest B&M electronics store in the country has a policy that is better.

I know Cingular, er AT&T at least has some sort of guarantee in their contracts that allows you to return a phone within x days (VZW is 30 days, I think it was 14 when I last had Cingular). I'd suggest that iPhone users who are eligible for it, take advantage of it to get the reduced prices. Unless of course that clause is blacked out in the iPhone contracts...