looks like it will still locked with the respective telco although it is contract-free. just like the O2 Pay n Go version of iPhone in UK.
btw from what i've read, O2 UK will unlock the prepaid version of the iPhone after 1 year of usage (with a fee i presume). dunno if AT&T will implement the same way. looks like it will be a good news for the "oh i dun want the unlock version" type of people, if got some relative from where the iPhone is purchased.
until then, use the iPhone with unofficial unlock. nyum nyum nyum. hope the new iPhone can be easily unlocked.