Like PZ, I can’t get very excited about the question of free will. I agree with him that for free will to be anything other than an illusion, our minds would have to be able to reach into our brains and change it’s behaviour. Minds would have to be intangible things, independent of brains, and this is demonstrably (and trivially so) not the case.
I’ve never been able to understand why people find it so difficult to accept that we could be fooled by a sensation of free will. It certainly feels like we can make choices, but what reason do we have to assume that makes it true?