Two years ago, I had a long drunken conversation about this subject with a lawyer here in Japan that sometimes handles immigration issues. He said that there are a number of ways in which an American can lose his/her citizenship wihtout specifically renouncing it, and one of those ways is to accept and use a passport from a nation that does not recognize dual citizenship.
Since Indonesia does not, if Obama ever traveled anywhere under an Indonesian passport, he had lost his American citizenship at that point, regardless of where he was born.
Further, it was that lawyer’s opinion that even if he had regained American citizenship through the naturalization process afterwards, he would still be ineligible for the Presidency because at that point he would be a naturalized US citizen, not a natural born citizen, even if he had been born in the Lincoln Bedroom of the White House.
I believe she worked for Timmy "the tax cheat" Geitners FATHER. Correct me if I'm wrong.