If he's a bastard, then his mother fails to fulfill the citizenship requirements that were in effect at the time of his birth.
If his mom was not a citizen, then neither is he.
Not that simple. If he was born in Honolulu, he's in. No question.
If he was born in Kenya, and BHO Sr, and Stanley Ann were married, he's a Kenyan, eligible for dual citizenship, but never the presidency.
If he was born in Kenya, and mommy wasn't married, then he is a US citizen, or not a US citizen, depending on whether you use the law that was in effect in 1961, or the laws that were amended later to cover children born in his circumstances, and whether you read the age and residency requirements for his mother with your left eye, or your right eye, and the phase of the moon, and the mood of the Supreme Court.
Either way, pretty much everyone agrees that being born on US soil means he's both a citizen and natural born, and is therefore eligible to hold the office of the President.
If he was born in Kenya or Canada, he could still be or not be a US citizen, but maybe not a natural born one, depending on whether jus soli or jus sanguinis (by soil or by bloodline) takes precedence.
I lean towards jus soli, if you weren't born on US soil, you're not "natural born" for the purposes of holding the highest office.
Unfortunately, that means that Panamanian born McCain who is of unquestionable loyalty and allegiance isn't constitutionally qualified in my book, but a Hawai'ian born, marxist, hate America first spoon-fed member of a destroy America faith, Obama is.
*double sigh*
See? Simple.
Try explaining that to any randomly selected voter...
(David? Did I miss anything or make any glaring legal errors?)
Oh, if the 1790 law takes precedence, then McCain qualifies as a natural born citizen regardless of the location of his birth...