Do you believe in an objective morality capable of being scientifically investigated (a la Sam Harris *or others*), or are you a moral nihilist/relativist? There seems to be some division on this point. I would have thought Less Wrong to be well in the former camp.
Edit: There seems to be some confusion - when I say "an objective morality capable of being scientifically investigated (a la Sam Harris *or others*)" - I do NOT mean something like a "one true, universal, metaphysical morality for all mind-designs" like the Socratic/Platonic Form of Good or any such nonsense. I just mean something in reality that's mind-independent - in the sense that it is hard-wired, e.g. by evolution, and thus independent/prior to any later knowledge or cognitive content - and thus can be investigated scientifically. It is a definite "is" from which we can make true "ought" statements relative to that "is". See drethelin's comment and my analysis of Clippy.
Natural selection favours some moralities more than other. The ones we see are those that thrive. Moral relativism mostly appears to ignore such effects.
It isn't an accident that there are no universal mandatory incest moralities out there in recorded history. That's not actually enough to prove moral realism is true.
In short, there are universal morally relevant human preferences created by evolution (i.e. hunger, sex drive). That doesn't show that evolutionarily created preferences resolve all moral dilemmas.