Both Apple and AT&T don’t have no-commitment pricing options on their websites. Apple states on its US website:
At launch, AT&T said that they’d sell iPhone 4s without contract for $599 and $699 for the 16 and 32 GB versions. Now you can’t buy it without a plan online at Apple or AT&T for any price.
(Update: AT&T has contacted us and stated that there is no difference in policy on their end and they can’t account for Apple’s website. Also, you can only buy a no-commitment iPhones in an AT&T store, there is no way to do so online [which seems insane because less paperwork has to be filled out])
(Update 2: Apple contacted us to first say that you could buy the no commit iPhone 4 in a store but not online)