There seems to be some division on this point.
I might be mistaken but I got the feeling that there's not much of a division, the picture I've got of LW on meta-ethics is something along the lines of: values exist in peoples heads, those are real, but if there were no people there wouldn't be any values. Values are to some extent universal, since most people care about similar things, this makes some values behave as if they were objective. If you want to categories - though I don't know what you would get out of it, it's a form of nihilism.
An appropriate question when discussing objective and subjective morality is:
People here seem to share anti-realist sensibilities but then balk at the label and do weird things for anti-realists like treat moral judgments as beliefs, make is-ought mistakes, argue against non-consequentialism as if there were a fact of the matter, and expect morality to be describable in terms of a coherent and consistent set of rules instead of an ugly mess of evolved heuristics.
I'm not saying it can never be reasonable for an anti-realist to do any of those things, but it certainly seems like belief in subjective or non-cognitive morality hasn't filtered all the way through people's beliefs.
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.