NoGoodNick - September 21, 2012 at 7:16pm
There's an issue with that, as no one is yet sure whether you'll even be able to ever buy an "unlocked" phone. It seems that the 4G/LTE requirements are hardcoded into each phone, meaning that you can't just switch from one network to another. Don't know if that'll affect 3G or not, but it means that you can't take a 4G phone from the US and run use it on a different network in another country.
Hopefully Apple has an answer to this, as it's a sore point with a lot of people, but so far they've been silent about it.