I have a question. Let's say the son of the US ambassador in Japan is born in Tokyo, can he become President? He's foreign born?
The Constitution says "natural-born citiizen", that is someone who is a citizen by a nature of his birth. This is distinguished from a naturalized citizen.
When Milt Romney's father (George Romney) was running for President, there were questions that he might not be eligible since he had been born in Mexico. In that case, it might not quite have been as clear cut, since I think his grandfather was part of a Mormon settlement, rather than residing temporarily.