Let me be the first to say that I do not think McCain's reference to Obama as "that one," which is already getting a ton of attention in the post-debate coverage, is a big deal. It is not the singular of "those people." McCain has always had a sharp tongue and an irreverent, almost cranky, sense of humor. You know, befitting an old uncle or grandpa.
I, for one, read no racism into the comment. Condescension, yes. Racism, no.