If you buy an iPhone and don't have AT&T service, it looks like Apple will be treating your iPhone as an iPod--with no 2 year service guarantee or even, for that matter, a 90-day service plan. Jake Dugard cancelled his iPhone account receiving poor AT&T reception. When his phone stopped working properly shortly after, he was told that Apple would not service his phone. Repairs depend on an active agreement.
It makes sense to me that Apple offers a much longer service time for under-contract iPhones than it does for iPods, but it doesn't make any sense that a no-contract iPhone isn't covered at least under the iPod's one complimentary support incident within the first 90 days of product ownership.
Dugard and/or his friends apparently recorded his service calls but, as an update, has now removed them for the time being from public view. If you followed the earlier link and cannot find them, that is why.
Thanks to iPhoned Home
Update: Quoting the relevant text: "iPhone comes with one year of hardware repair service coverage and up to two years of technical support during the time your wireless agreement remains active with AT&T."
Update 2: Apple 1 Year Limited AT&T warranty here. Have at it. (Thanks to Kai Cherry)
Update 3: An anonymous iPhone Product Special writes in: "During the first 90 days of ownership, iPhone customers experience unlimited support. For all active AT&T account holders, iPhone customers continue to receive unlimited support for the duration of their iPhone's 2 year service agreement. If a customer discontinues their AT&T service before the 90 days of complimentary support, they are still provided with support, and then covered by the 1 year hardware warranty, during which, if they call for support, have a pay-per-incident charge." /p>