I don't think McCain needs to put a woman or a minority on the ticket to win in November. The Democrats have gone so far left, I think it's going to be a landslide for him. But, this is the land of the free and the home of the brave and I'm a little disturbed by the as yet, undefeated streak of "Two Snow White Guys" for the presidency.
Now I wouldn't vote for someone just because of their ethnicity or gender, but I know there are people of color and women out there more qualified to be president than Dan Quayle and Al Gore. I understand why more of them don't run. It's the same reason most emminently qualified people, white, black, hispanic, asian, eskimo, male or female wont run. The process is degrading, dirty, and no matter how well you do, at least 40% of the country and most of the world will hate your guts for it.
Finding a qualified minority candidate is not the problem. Convincing them to run for public office is. Appeal to their patriotism, their ego, their sense of adventure.
Condaleeza has said she doesn't want the job (smart woman), but I've heard it said that she has never turned down public service when asked. Go ask.