If you must have Apple's iPhone, but live outside the US or don't like AT&T, don't spend money at one of iPhone Sim Free's franchise outlets, get it for free off the people who do this cracking stuff for a hobby.
This, coupled with a US$200 price drop, makes me tempted, very tempted indeed. This means an iPhone will cost you nothing more than buying the unit and the usual recharge costs for your existing SIM.
Of course, follow the instructions carefully with any software like this. Nobody can assume responsibility for "bricking" your iPhone but you, really.