A couple thoughts here... I've been kinda waiting for a thread on this to pop up...
I am no birther by any means. That said, Obama being president and being constitutionally ineligible would certainly go down in history as being one of the greatest frauds ever carried out on the American people.
I do not believe that any realistic level of "proof" would be enough for many in the birther movement. It's the same as dealing with any conspiracy theorist. Short of allowing absolutely everyone who doubts his citizenship to personally handle, inspect, and do whatever they need to do with the paperwork in order to be convinced, there is no way you will ever prove it some people. Obama would certainly have the resources to falsify any documents though, so even personally inspecting the paperwork probably wouldn't convince many.
Take the moon landing conspirary theorists. Short of actually having set foot on the moon themselves, no level of evidence will ever convince them. Ergo, IMO, these birthers are really not worth paying any attention to. If they were a rational group, maybe it would be worth considering, but they aren't in many cases. Obama supporters however that bring race into the issue are only lowering themselves to the same level. Disagreeing with an African American leader does not necessarily make you a racist there I said it.
Here's my real wonder... just for the sake of interesting discussion, let's say that it was somehow proven that Obama was not born in the United States. He is therefore constitutionally ineligible to be president, which means that ultimately, his presidency was never legal.
What happens to all of the bills, executive orders, and everything else that he officiated as president? Conceivably, all of his presidential acts would be null and void. The impact would be staggering...
Additionally, what does that do in the order of succession? Since Biden was elected on the same ticket, it stands to reason that he is ineligible to serve as president in the order of succession. That would make the president Boehner, since he is third in line, and since his position as speaker had nothing to do with any elections associated with Obama. The party would shift. Amazing when you think about the ripple effect that this would have. The really scary though is the uprising that would occur in this country. Although I am a complete believer in the rule of law, one could argue that it's almost better that should Obama not be serving legally, that the truth not come out.