Tim Wu is apparently a pretty smart guy when it comes to copyright laws and he has taken the time to weigh in on iPhone unlocking. He even says he told the Apple employees at the Apple store where he bought his iPhone that he was intending to unlock it and they still continued to sell him the $400+ iPhone.
He alludes to the fact that due in part to the way in which the iPhone is sold, no subsidies and no in store activation, that there is not even an implication or unspoken agreement, let alone a written one, that says when you buy an iPhone you are agreeing to become an AT&T customer. The only thing you are agreeing to is to pay $400 for your iPhone and to take complete ownership of it for whatever purpose you see fit.
He likens it to buying a car from an auto manufacturer such as GM and then adding non GM parts to it, or going to another mechanic other than the one at the local GM dealership for servicing. Once you buy the product, its all about what you want to do with it, and what’s convenient for you.
So it’s legal, there are possible consequences, namely if you unlock and try and upgrade to Apple’s latest firmware, it wont work. Your warranty will also be voided and Apple will no longer repair your iPhone, but there are 3rd party companies online these days that will do that for you, not under warranty, you will have to pay, but you can still get your iPhone fixed without going to Apple.
Unlocking an iPhone is legal [via boingboing]