Only an unbranded phone (never sold/used by At&t) can be activated on At&t without the required data feature. Blackberry or iPhones (any model) would not be exempt.
One sidenote, even users of the Nexus One sold by T-mobile were required to carry a data feature. There are several posts about Nexus One users getting a notice from At&t.
i am on at&t and i was wondering if it was possible to buy a smartphone like an iphone or blackberry off of ebay and put my sim card in it and it still work and everything but w/out a data plan? and also could i still download games and apps on the iphone as long as they dont connect to the internet?