Michael Totten hosts a vigorous discussion of a topic I find fascinating: the greater tolerance that has apparently evolved on the right for centrists, relative to the left.
I think the main reason this has developed is because of how institutionalized the modern left is. Unions, academia, interest groups, strictly moderated discussion boards: all very clique-ish. Memes bounce around those echo chambers and consensus reality becomes whatever they agree it is. When they emerge from their lefty cocoons, blinking and stumbling in the light of day, they're forced to deal with the fact the other 70% of the country doesn't agree with most of their insular version of reality. I think it honestly perplexes and enrages them when everyone else doesn't yell "Right on! Bush is a Nazi!" The center-right is anchored in talk radio and the long tail of smaller blogs, and so is forced to freely debate things more, to their sanity's benefit.
As a mostly-libertarian, I instinctively distrust institutions. They tend to ossify, suppress internal dissent, and however well-intentioned they inevitably succumb to "mission creep" in order to justify their continued existence and growth. Thus you get a tragedy like the once-noble NAACP gradually morphing into a left-wing hate machine, which in turn drives centrists farther away. I offer as further proof the one area of the right that is least hospitable to centrists, which is of course the Religious Right: the aged institutions of religion. Like their counterparts the Religious About Being Leftist, their self-righteous beliefs are often unshakeable by mere fact. (As a Christian, I am happy to remain basically nondenominational.)