Can we stop the Condoleezza Rice speculation, please?
I know you didn't ask me, but I don't think Condoleezza Rice has a prayer in the 2008 presidential election. As a candidate alone, she's totally lacking in campaign experience. And, worse for her, having spent the last five years (and counting) working for one of the most divisive administrations in history doesn't give her much of an opportunity to define herself as an independent-minded, take-charge kind of person.
That's how she stacks up considering her generically; those facts would apply to anyone in her position. However, race is an added factor. Black Republican candidates depress turnout among Republicans, which is why you see so few black Republican candidates and still fewer black Republican officeholders. Look at Lt. Gov. Michael Steele in Maryland: his being black has taken the air out of his U.S. Senate candidacy (but, to be fair, he's also a bloviating buffoon, which is a quality that even Republicans don't care for.)
Now to be fair, having a black Democrat on the ticket has been shown to depress turnout among Democratic voters, too—but not as drastically as black Republican candidates do to Republican voters. This is not admirable or tolerable, but that's how it is. This is not, however, a reason to discourage blacks to seek office, and I maintain that quality candidates of any color have a duty to step forward and run. Places that would never have dared elect Catholics or Jews or women to their state legislatures or to Congress have come around; I believe that the whole country can come around where race, color and creed are concerned.
The above calculus applies to the Rice question (and the Powell question, and the Steele question) because the Republican Party is the conservative party, which means it embraces stasis and stands against progress. Tolerance of non-white, non-male candidates is progress, so such a candidate couldn't hope to get through the primaries, so the notion of a Rice for president campaign is more academic than anything else. If Condi Rice made it to the nomination, then we'd already be talking about a very different America from the one we currently live in, so I offer no opinion about that scenario. The America where the Republicans would nominate Rice is so far from existing at this point, I couldn't even begin to guess what the voting patterns in that place would be. I will say, however, that the voting patterns in the America I know would allow the Democratic candidate running against the Republican candidate Rice to crack 500 Electoral Votes.
The only black Democrat I'm aware of who currently has a shot at becoming president is Barak Obama, but that can't happen in 2008. He's still too new to the Senate; he still needs to build a record to run on and build up his connections on Capitol Hill. I think he's capable, and I'd be very surprised if he never runs for president. I'd be even more surprised if he runs for president before 2016. I have a hunch Obama will show up as someone's running mate before he runs for president, but at this point I can only speculate; I can't see the future.