Larry Lessig on Sarah Palin
I have a number of reservations about the details of Larry's argument, but the one I thought worth mentioning is the question of what kind of experience counts. In the video—worth watching—he runs through all of the past VP's and concludes that only two, both Republicans, were arguably about as inexperienced as Palin. In two more cases, the experience he lists consists of being a founding father; it isn't clear to me that that counts as training for the job of being President.
More important, quite a large number of the VP's, I would guess about a third, had no executive experience that he mentions—they had been representatives and/or senators. It's true that being in Congress involves many of the same issues a President will have to deal with—and, of course, part of the job of Vice-President is presiding in the Senate. On the other hand, the real function of a vice-president is being President, if and when, and being a legislator is not the same sort of job as being an executive.
To take a slightly stretched analogy from my profession, being an academic, even a Nobel Prize winner, doesn't qualify one to run a university, and being a university president isn't, or at least ought not to be, adequate qualification for a position as a tenured faculty member in an academic department.