This has been done many many times before but I'm unsure if the method has been so vocally projected in a long time as to the step by step method so the common man can do it, because these phones are sold. There are many people and sites advertising "unlocked phones", including Iphones. I guess with the open source revolution in technology, we really can't be surprised.
Apple has is at fault in this with lax software and hardware that allows people to unlock the Iphone. Apple would probably come up with a countersuit about AT&T networks but I can't imagine what details that would include.