For an interesting take on all this talk of Senator Barack Obama transcending race, see this post by Too Sense. One Drop argues that those speaking of Senator Obama transcending race are actually exhibiting a kind of racism. The way some people speak of transcending race, you get the idea that Obama is making headway with white voters because he's somehow risen above the fact that he's black.
I very much appreciate One Drop's affirmation that black people who have "made it", such as Secretary of State Condoleeza Rice, are still as black as they ever were and as black as anyone else who is black. Colin Powell, who occupied high positions both in the military and the civilian government, is black. He didn't transcend his race. It's insulting to them and to all black people to speak as if these people did.
I must note that it isn't just white people who think this way. Black people can operate from the same assumption. They don't usually say Colin Powell transcends race, though, as white people operating under this assumption will. They say he's not really black and that he's sold out to the white power structure by his willingness to hold a position in it. It's a pretty negative attitude toward the person, whereas this idea of transcending race is at least on the surface positive. But both come from the same false assumption, that blackness is incompatible with success in a world dominated by white people (and most often white men).
On the other hand, as I commented at One Drop's post, there's something very different that someone might mean by the expression "transcending race". Rather than seeing Obama as somehow beyond his race, as if his race doesn't matter at all, some people (I am convinced) are seeing him as standing for more than the issues that are particularly associated with being black. They see most blacks who have run for president in the past, most notably Al Sharpton, Carol Moseley-Braun, Jesse Jackson, and Shirley Chisholm (but most definitely not Alan Keyes) as being too focused on concerns that are black, in a way that white people who haven't adopted those concerns would be less attracted to their candidacy. In other words, Obama has a wider attraction because he deals with wider issues, and he presents the issues that are specifically related to black people in a way that white people can see that they support them too.
Now there's a different danger with this kind of "transcending race". If it assumes (or gives the impression) that so-called black issues aren't important for non-blacks to be concerned about or that what's bad for blacks isn't bad for everyone, then I think that's bad. It displays a real insensitivity to race issues. But I don't think it's quite as bad as the kind of "transcending race" talk One Drop points to. I'd say that it's a pretty unfortunate feature of the Obama campaign but one that he can do little about at this point (and I suspect wasn't responsible for in the first place). But those who participate in it are perpetuating something racially harmful.
There's actually a third group of people talking about Obama as transcending race who do neither of the above. They see him as transcending race but see that as negative. They're well aware of the fact that, for many, transcending race can be one or both of the above two things. Then they accuse Obama of inappropriately trying to transcend race (or perhaps being used by others to do so) in order to appeal to white people. Those who make this complaint will thus see him as a sort of race traitor. I don't think it's fair to go that far with it, but I do think a lot of the reason why he's got the support he's got from white people is that they see Obama as a safe black. Talking about someone as transcending race in that sense can be perfectly legitimate when it informs us about a real racial dynamic, one that can be dangerous. So it's not clear to me that all talk of transcending race is bad, even if the first kind is very bad and the second is at least unfortunate.