Let the hive mind of Engadget get that for you.
"As someone who doesn't reside in the USA, I was wondering what would be the best way to get internet for my computer in the US for a couple of weeks? If it were Europe I know I'd look for some prepaid data. Is there anything similar offered by American carriers? A MiFi or a data SIM that I can tether from would work, but I'm trying to maintain a tight budget. Help!"
To the person who was like "this is the law," um it is against the law to hack your iPhone in the first place. You did sign the contract saying you may not change services (i am 100% sure you will sign such contract when you sign up with Apple), and you did it anyway. Now your hardware is broken, Apple can say it's because you hacked your iPhone, which you shouldn't have done anyway. This is with EVER electronics, if you say overclock yoru computer and it fries, no judge in the world will rule in your favor.
Actually there is an exception to the DCMA (apple's favorite bit of legislation) that allows people to unlock cell phones to a new carrier. If I understand the legislation correctly the law allows for the people to hack the phone, just not advertise the hack. Therefore nothing illegal is going on with apple, just a violation of AT&T's contract which should have nothing to do with a hardware warranty on consumer electronics.
Um - it's not "against the law." If anything, it would only be against their warranty. Do some research.