We don't really know how much race was a factor in this election, do we? In fact, throughout the campaign the factor which seemed to be most important was age: if you were under 45, of any age, you were most likely to vote for Obama, if you were over 45 you were most likely to vote for McCain.
There is a trend that African American candidates do worse on election day than the polls indicate. That seemed to happen here to a degree-most polls showed Obama ahead eight points or so, he finished six points ahead of McCain. So we can conclude, at least for this election, that race had some effect, but not enough to change the outcome. And the effect does not appear to be large.