Below is my response to my boss asking me what I thought about the NYtimes Article that reports Obama's checked the "black" box instead of taking advantage of the option to "write-in" his race/races:
I think that Obama's checking the "black" box was more political than a genuine manifestation of what race he "feels". Perhaps in a way he does feel "black" since he projected/marketed himself as such for the purposes of being the "first black president". But ultimately i think he did it to be consistent for the America that isn't yet comfortable with bi-raciality.
Much of black America voted for what they saw/believed to be a "black man". Common belief in black communities "if you look black then they think you're black, so you are black" and black Americans voted for a man they could call their own, his "story" negligible. White Americans voted for a "black man" that speaks like a white man. Obama is the anti-intimidator; he doesn't challenge or appeal to white America for entry into their sphere/club by claiming his (true) whiteness on the census. He, in a sense "knows his place" and keeps there. But i don't think that this is at all an Uncle Tom move, i think it's more about pushing the limits of race intermittently, somewhat implicitly, stealthily.
in short, am i surprised? no. I think he feels as biracial as you and I but knows that it's an identity that is burgeoning, not yet marketable on large-scale politics, to the body politic. he owes it to his base (black americans) and he can't scare off the white Americans.
warmest regards on this warm day,