The reserves/pre-orders are contract only.
I reserved one at 10 pm on contract. When I showed up, I asked if they would sell it to me device only. They agreed, and cancelled my contract extension. it didn't seem like a big deal or unusual request. Boylston store, Boston.
Edit: so exactly the same experience as jlp2979, except I was already an AT&T customer, so they didn't cancel my service, just the new contract extension.