So, due to a family issue, there's the distinct possibility of me moving from the US to the UK for an extended period of time. I have a 3GS already, locked to AT&T (though Jailbroken, I have no need to unlock, I have a nice discount on my plan through work) but if came to the UK, would O2 unlock it? The process, from what I gather, is to insert your SIM from your new carrier into your O2 phone, plug it in to iTunes and it does the rest. Would this work for a US phone? Pop Vodaphone SIM in, change iTunes store to the UK store and bob's your uncle?