I've been reading about the unlocked iPhone 4 that will be available internationally, but not in the US. I'm not all that familiar with the nuances of unlocked GSM phones, so maybe someone can answer a few questions... First, it seems like having an unlocked iPhone could be beneficial in a country where there are multiple GSM carriers, but would an unlocked iPhone really be all that worthwhile here in the US? Here, AT&T and T-Mobile would be the only two options. Of those two, I'd say that AT&T is generally regarded as the better of the two, and since AT&T is already the exclusive carrier of the iPhone here, would having unlocked iPhones here in the US really be that beneficial? Secondly, if someone here in the US acquired an unlocked iPhone from Canada or elsewhere, then A) Would they be able to purchase service from AT&T or, if desired, from T-Mobile? B) Would the monthly service charges be the same as if one was under contract with the carrier, or do carriers have separate (and likely more expensive) service plans for unlocked phones? C) Would a service contract be required, or is month-to-month service with no cancellation or ETF penalty available for unlocked phones? D) Would an unlocked iPhone with AT&T service work exactly the same as an iPhone locked to AT&T, or would there likely be some features or services that wouldn't work as well or quite the same on the unlocked phone as with the locked phone? E) Are there a fair number of unlocked iPhones (previous models) already being used here in the US, and if so, are any any benefits of going with T-Mobile over AT&T? My questions are more out of curiosity, as I'm certainly not planning on acquiring an unlocked iPhone any time soon, but thanks to anyone who might be able to answer my questions.