Do you like the LW wiki page (actually, pages) on Free Will? I just wrote a post to Scott Aaronson's blog, and the post assumed an understanding of the compatibilist notion of free will. I hoped to link to the LW wiki, but when I looked at it, I decided not to, because the page is unsuitable as a quick introduction.

EDIT: Come over, it is an interesting discussion of highly LW-relevant topics. I even managed to drop the "don't confuse the map with the territory"-bomb. As a bonus, you can watch the original topic of Scott's post: His diavlog with Anthony Aguirre