People born outside the US are not eligible to be or run for the Presidency, it is not just a matter of being a US Citizen by birth, which he is possibly due to his mother (although she might have been too young to pass this on to her son). At any rate, McCain was born in Panama on a military base so some say that is the same as US soil, but I don't really believe he is strictly eligible either.
If Obama was born in Kenya he is not eligible.