He wasn't born in America. So, unless we have the quickest organized Constitutional Amendment ever, poor, 'ol McCain seems cooked to me.
"No person except a natural born Citizen... shall be eligible to the Office of President." Oopsie! I actually remember this tidbit coming up in my Con Law class back in the day, when I was pretty outraged that someone born in an American base overseas wouldn't be eligible to become President. I even think it's ridiculous that someone who's lived here for 15-20 years couldn't run either - but such is this country's highest law.