An Australian hacker supposedly managed to make outbound calls and SMS on his iPhone. Instruction page. Video after the jump.
Unfortunately it is not a foolproof hack as you cannot get incoming calls or SMS. With a little modification EDGE and SMS can be used(in/out). This requires a SIM card reader/writer but if your dying to use your iPhone for something other than an MP3 player, then here is your chance
[via NewLaunches]