All this matters, for if Obama once was a Muslim, he is now what Islamic law calls a murtadd (apostate), an ex-Muslim converted to another religion who must be executed. Were he elected president of the United States, this status, clearly, would have large potential implications for his relationship with the Muslim world.
...but I don't.
In fact, I cannot see this as an issue other than as perhaps the radicals like Al Queda might see him as an even more legitimate target than they already see our president, and perhaps that Saudi Arabia and Iran might be put in a tight theological spot in being forced to deal with an elected leader who under their (allegedly) literalist interpretation is a heretic.
However, that very thing would probably work in our favor by forcing the point into sharp relief, that extremist orthodoxy in religion does not mix with intra- and inter- national governance.
Personally, I am not voting for Obama, but it is strictly because of his politics and the party he is representing that is trying to put a new and more conservative face on an infrastructure that remains unchanged from the previously revealed hyperdelusional leftism we saw with the Dean campaign. It's like putting a new paint job on a wreck and thinking that is enough. It's a pretty wreck, but the Democratic Party is still a wreck nonetheless.