Where are you located? In the UK O2 have announced that they will be available pre-pay (i.e. without a contract/credit check). I do not believe that this has been announced in the US so may not be available there.
Well at this stage it's looking like you will need to pass a credit check and sign a new contract to get one. This may change closer to release date, or perhaps after release. Your best bet is to ask ATT.