His mother was a U.S. Citizen. So, it doesn't matter where he was born, he is a natural born U.S. citizen. So, why would he lie? I'm all for a good conspiracy theory, but only when they can be convoluted to make a bit of sense.
I've heard that Obama won't release his college transcripts because he registered as a foreign student in order to improve his chance of acceptance or something like that. I have know idea if this is true, but at least he has some motivation to have done this. The birther stuff is just nonsense fanned by liberals to cause some conservatives to be distracted from what is important.