Dual citizenship is no bar to the Presidency. My kids will be, at birth, automatically citizens of the US, Canada and Serbia. That is perfectly legal and will be no bar to their potentially running for the Presidency.
And where on earth did these people ever get the idea that it was? Can Russia, or Panama, bestow citizenship on McCain and disqualify him? Of course not. My mother is an immigrant, and since she had not been naturalized at the time I was born, I could have, until age 21, applied for dual citizenship. I didn't but doing so would not have cost me my US citizenship.
My mother renounced, under US law, her prior citizenhsip, when she was naturalized. In the eyes of the US Government, she is an American, not a dual national. But when we visit the old country, she gets a permanent entry stamp on her US passport, and the rest of us get a tourist stamp. The land where she was born still considers her a subject, welcome to come and stay, but that attitude on their part does not in the least affect her citizenship here.
People, put down the popcorn, go to the McCain website, and sign up to help defeat Obama.