WebProNews

You say "One snag, as noted by ArsTechnica is that it may be unrealistic for consumers to believe they can transfer their iPhone, for example, from AT&T's GSM network to Verizon's CDMA. However, generally all that takes is replacement of the SIM card, and there are already iPhone hacks in place, even thought the iPhone was designed for one network only."

CDMA and GSM are 2 different technologies that have different chipsets in them. Unlocked or not, it is NOT possible to take an ATT phone and put it on the Verizon network and visa versa. Verizon and CDMA do not utilize Sim cards, they use ESN's. Unlocked phones work well in Europe because all the networks are prominently GSM. And thus your statement would be correct, you can just take the sim card out, pop another on in, and you're good to go.