OK, I must have been asleep for a month- I actually had no idea a fully priced at&t iphone 5 comes unlocked right out of the box. This is almost unbelievable to me as I have been waiting for Apple to announce the unlocked phones to become available. I am a T-Mobile customer.
It shouldn't be a surprise as the iPhone 4/4S were unlocked from the Apple store when paying full price for the AT&T version. And technically it isn't unlocked until you hook it up to iTunes the first time.