From an interesting article found on Counterpunch :
"If anything, America’s unquestioning identification of Obama as a ‘black’ candidate is deeply problematic. It demonstrates that the United States remains firmly rooted in ideas of race that go back to the era of slavery and Jim Crow Laws.
Obama’s mother was white and, apparently, so were all her forebears; while his father was a black African and, apparently, so were all his forebears. Obama is biracial – half-black and half-white. Why did that, automatically, make him black? If being half-black makes Obama black, by the same logic we could identify him as white.
Why didn’t we?
The answer is rooted in the history of racism in the United States, in the categorical rejection by whites of the mixing of white and black races. A person was ‘black’ if it was known that there was black ancestry, anywhere, in her lineage. This was the arithmetic of white racism. White + Black = Black."
Read : http://www.counterpunch.org/shahid11192008.html.
Or, for those who expect miracles :
"A president is only the visible face of lobbies and corporations who own this country and its ‘elected’ institutions. Unless the people are out in the streets demanding change, there will be none. Populist election-year slogans are forgotten once they have done their job at the polling stations."