If I understand aright, it's not a question of his being a citizen, but whether he was born in the U.S. I believe it's a requirement in the Constitution that the President be born here.
No person except a natural born citizen, or a citizen of the United States, at the time of the adoption of this Constitution, shall be eligible to the office of President; neither shall any person be eligible to that office who shall not have attained to the age of thirty five years, and been fourteen Years a resident within the United States.
Article II, Section 1
Then McCain would also be ineligible, which is maybe what some people would want (a primary do-over?).
At the end of the day on January 20, 2009, either McCain or Obama will be Prez.
No. It is not. The requirement is that you are a "natural born" citizen, not a "naturalized" citizen. Every citizen KNOWS if they were naturalized or not, becaus it requires work and taking an oath, etc. Obama was certainly not Naturalized.
John McCain was not born here, he was born in Panama. None the less he was a citizen since birth. He did not, at any point, have to through naturalization. That is because both his parents were US citizens, which gave him automatic "birth right" citizenshp.
The question with Obama is 1) was he born in the USA (which would give him birth-right citizenship and 2) if not, what law they either gives or denies him citizenship based on his 1 parent being a citizen.
The laws circa 1960 were written in such a way that one parent being a citizen, child born in a foriegn land - citizenship was NOT automatic. This was to prevent a flood of babies fathered by US Servicemen while abroad (sorry!).
Some have claimed that a later law retroactively changed this to include cases like Obama. I'm not sure which is true.