Bret Baier, anchor for Fox News' serious news hour, has a very nice short column on who is a natural born citizen. "Natural born citizen" is a status the Constitution says you must have to be elected president or vice president.
It turns out the Constitution's authors didn't clarify their intent, and so Federal law 8 U.S. Code Section 1401 is left to define who is/is not a natural born citizen. The answer isn't simple.
It appears that the Supreme Court could choose to weigh in on the subject and attempt to divine the intent of the drafters. Until that happens, the rather complex code indicated above is the rule. Baier says he is citing the research of columnist Byron York of the Washington Examiner.
As Baier explains it, that law makes clear that regardless of where he was born Barack Hussein Obama is a citizen because his mother was a citizen. That BHO doesn't act like a natural born citizen is a whole other issue, one I attribute to his unusual, multicultural and expatriate upbringing.