Vernunft at the The New Skeptic discusses Christopher Buckley's defection from the 'right' to the 'Obama'. I think Vernunft gets it right enough: Buckley's departure is looking less and less like a serious, political decision and painful exile and more like a self-serving attention grab. Usually it works out like this: person defects, presupposes the hatred of their former comrades, writes book. It amazes me that these brave souls survive the process.
More often than not, these incidents involve someone leaving the Right for the Left, and making a big, big deal about it. Do people leaving the Left for the Right do the same thing? I can only speak of Canadian examples, but when David Emerson did it (he had been elected to the House of Commons as a Liberal MP and then joined the Conservatives a few days later), he played down the entire affair. However when Belinda Stronach left the Conservatives for the Liberals, she made sure it was national news for several days in a row. Emerson made sure not to say anything disparaging about his former colleagues; Stronach made it as if she was being persecuted out of the party. I don't doubt that both switched out of personal gain, but the way each handled their situation couldn't have been more different.