Actually, restricting reviews to members only helps to prevent idiots from coming on-site and giving fifty people in a night '1' ratings. If a member does that, the moderators can do something about that when they downgrade the idiot to 'guest' status. At least, I assume they can. Tourguide?

Your idea of the automated review process would be a little bit of a pain in the ass to those of us who read with one hand, but it's worth considering.