Ping.
There is no evidence available of any nature anywhere that Obama was born in Hawaii or anywhere else in the US.
On the other hand, there is abundant evidence that he was born in Mombasa, in Kenya.
If he was born in Kenya, 8 USC Sec. 1401(g) makes it clear that he was not a United States Citizen at birth. The legal authorities describing the origin of the term "natural born citizen" make it clear that the clause was used by the founders for the purpose of requiring that the President of the United States have been born within the geographical confines of the several states, probably to two US Citizen parents.
So the short answer is that absent a subsequent naturalization proceeding which may in fact have occurred, Obama is not a U S Citizen. And the prerequisites of a naturalization proceeding require him to exclude the elements of the status of "natural born citizen" under the Constitution.
Thanks for the ping Lucy. I have some catching up to do.