Lew, according to the Constitution, a president need only be a "natural born citizen." According to the US Code, citizens at birth include persons "born outside of the United States and its outlying possessions of parents both of whom are citizens of the United States and one of whom has had a residence in the United States or one of its outlying possessions, prior to the birth of such person."
According to wikipedia, there is some disagreement over whether a "natural born citizen" is the same as a citizen naturalized at birth. Goldwater and George Romney were also not born in US states (though Goldwater was born in American Territory). Neither of them won and qualified as a full test case. McCain would be the first, but I tend to agree with the plain language of the Constitution (as I interpret it): Should McCain be president, where he was born would probably be the least unConstitutional thing about his administration!
Thanks to Scott Garner, Dick Clark, Brian Martinez, Jason Ditz and Max Chiz, with whom I've been discussing this question over the last few minutes.
