BTW, I love the last paragraph of Steve Benen's post on this matter:
I can think of plenty of politicians who are genuinely, unambiguously dumb. I've even met a few, and marveled at how they were able to attain any kind of political responsibilities, given their limited intellectual prowess. But I don't think I've ever seen a politician as conspicuously unintelligent as Sarah Palin gain national prominence. She represents the very worst American politics has to offer, and the embarrassment she brings to the political system is severe.