That changed on Tuesday, when Apple announced it would in the U.S. You're responsible for procuring your own micro-SIM--that's the card that identifies you to mobile networks and lets you make calls--and you've got to line up a cellular contract. But other than that--and a modest payment of $649 or $749 to buy the device--an unlocked iPhone 4 capable of connecting to any GSM-based network is all yours.
The question is, why pay up for an unlocked phone? We can outline why this may be the right decision for you--as well as a few reasons you might want to stick with the lower cost model.
* : The iPhone does a lot of things seamless, but crossing over borders isn't one of them. Travel with your iPhone overseas and you can rack up some pretty stiff data roaming charges from your carrier back home.
If you have an unlocked iPhone, though, globetrotting becomes a lot simpler. Since much of the world uses the same GSM technology as the unlocked iPhone, you can take it with you on your travels. All you need to do is swap in a local carrier's micro-SIM, and you can use your iPhone just like you would back in the states. That's an attractive proposition for anyone who makes frequent trips abroad for business or pleasure.