OK, so I've been seeing Chris' argument on alot . . .
I understand that the cost of the phone is partly subsidized over a certain time period. However, you can't use that argument without looking at the numbers.
I was with Tmobile for 4 years until I got an iPhone in January. I upgraded several times with them. Their subsidy was spread out over the first 11 months and was basically done with the monthly charges for the PHONE SERVICE.
In the case of AT&T they are subsidizing it over an 18 month period. At the same time, they are charging a required $30 per month iPhone data fee. This was increased $10 for the 3G to subsidize for the phone. HOWEVER, they are still getting the $50 - $100 per month for PHONE SERVICE on top of that and do not have to pull the subsidy from that at all. Not only that, their phone service is MORE EXPENSIVE than Verizon, Sprint, and Tmobile. THIS IS DOUBLE (TRIPLE) DIPPING.
Not only that, but their text messaging rates are enormous compared to Tmobile!
While I know that it is reasonable for AT&T to make iPhone users wait 12 months to wait for an upgrade, 18 months is too long and is not inline with Apple's product cycling, so something needs to be done.
P.S. If you really want an iPhone 3GS, just buy it, and sell your 3G on Ebay. They're selling between 200 - 400 dollars right now.