Clark Goble at Mormon Metaphysics provides this link to an interesting paper on Frankfurt examples in free will by John Fischer. I am utterly unimpressed by Frankfurt examples, and I disagree entirely with the conclusions, but Clark is right that the paper is good.
As to why I'm unimpressed, I'll have to blog about that some time (hint: it has to do with the way choice itself is characterized in them); and then perhaps will see if my being unimpressed is a function of my ignorance or my savvy. But right now I'm going home to bed, so that's for a later time.