I've heard statistics from some sources as high as 97% of black voters will be voting for Obama, just google for some of it it's out there. Even if they're off and lets say it's only 85%, still.
If 85% of white people voted for McCain, it would be considered racist.
Check your statistics (and your assumptions). Democratic presidential candidates always get ~90% of the black vote; so, it's just unreasonable to suggest that this is because Obama is black. Kerry got ~88% of the black vote in 2004, while Gore got ~90%. Current estimates suggest that OBama has ~91% of the black vote, which is essentially unchanged. In the Democratic primaries, Senator Clinton was doing very well among black voters in polls, until certain incidents in South Carolina.
An inclined plane is a slope up. -- Willard Espy, "An Almanac of Words at Play"