He may or may not be a natural born citizen. The discussion only serves to detract from current policies and actions which deserve the public's attention. Tracy, you're right, the real question is his performance as president.
However, given the enormous # of times he has not only acted in conflict with the promises (that helped get him elected), but has also tried to violate federal law (e.g. TARP) - his deceptive actions/responses regarding his origin of birth provide one more possible data point in painting a picture of a man who wanted to be president so badly that he'd lie to anyone to achieve it.