One of the standard responses from the right-wing knuckle-dragging crowd to assertions that Obama will be hurt by racists who refuse to support a black candidate is to look at the high percentage of his support by blacks and say that this is racist in the same manner, because these blacks are voting for Obama because he's black.
It is not the same, and the reason comes down to attitude -- whether the decision is made on the basis of a positive or negative orientation.
First of all, we must recognize that the vast majority of blacks have voted Democrat for decades. Second, the Republicans and McCain have run a campaign that has nothing in it to appeal to urban or black voters, further emphasizing a shift to Obama on their part. And third, there has been overt racism on the part of the right. But my point goes beyond that.
In an ideal world, people would choose candidates solely on the basis of their policies and character, not other attributes, but we don't live in an ideal world. Many people will give preference to a candidate because they identify more with him or her, or because they perceive a natural link based on background or geography.
Choosing someone for these sorts of reasons may not be the way I'd like it to be, but at least it is being made out of a positive association. There's a big difference in choosing someone because you are excited about supporting someone like yourself, and voting against someone because they are different than yourself.
This happens all the time in politics and nobody even pays attention to it. For example, one of the "conventional wisdoms" in picking a VP has always been to choose someone who can "help carry a state". Why should this even be a factor? Because people like to vote for a "local boy/girl". So we saw a big spike in McCain's polling in Alaska when Palin was chosen (some don't realize that Obama had been competitive there up to that point, not that it mattered much.) This is done because of local pride and identification reasons. It may not be entirely rational but it's nothing nefarious.
We see similar things in other respects as well. For example, people were urging McCain to choose Lieberman as his running mate in part because his religion would appeal to Jewish voters in the swing state of Florida. We've also seen VPs chosen because of their age -- the Biden choice is arguably partially in this camp. And of course, there's the appeal to women angle of choosing a woman VP like Palin, or some of the support Hillary Clinton had.
Voting against a candidate on the basis of these factors is an entirely different matter, because it is based not on positive feelings such as pride or excitement but rather on fear, hatred and resentment. Voting for a candidate because he comes from your home state is not the same as voting against a candidate because he comes from a state you don't like. Voting for a woman because you are excited about a woman being elected is not the same as voting against a woman
because you don't want a woman elected. And voting for someone because you feel association with his race is not the same as voting against him because of race.
Are some black supporters of Obama racist? Almost certainly true. I would imagine that part of the increase in turnout to support him consists of blacks who would vote for a black candidate but not a white one. But I believe this is a very small number. Remember that blacks have, ever since they were granted the right to vote, had no choice in this regard -- they have always voted for white candidates. I can understand them being excited about the chance to support oine of their own for a change.