[Edit: Issues, Bugs, and Requested Features should be tracked at Google Code, not here -- matt, 2010-04-23]
Less Wrong is still under construction. Please post any bugs or issues with Less Wrong to this thread. Try to keep each comment thread a clean discussion of each bug or issue.
Requested features... sure, go ahead, but bear in mind we may not be able to implement for a while.
It seems like the only criterion for the rating of comment/post be the degree to which it contributes to healthy discussion (well-explained, on-topic, not completely stupid). However, there is an strong tendency for people to vote comments based on whether they disagree with them or not, which is very bad for healthy discussion. It discourages new ideas and drives away visitors with differing opinions when they see a page full of highly rated comments for a particular viewpoint (cf. reddit).
The feature I would recommend most for this website is a dual voting feature: one vote up/down for the quality of the post/comment, and one for whether you agree or disagree with it. This would allow quality, disagreeable comments to float to the top while allowing everyone to satisfy their urge to express their opinion. It also would force people to make a cognitive distinction between the two categories.
Even people like me who try to base their ratings independent of their agreement with the comment are biased in their assessment of the quality. It would be very healthy to read a comment you agree with and would normally upvote (because your quality standards have been biased downward) only to see that a large fraction of the community finds the argument poor.
Incidentally, you might allow voting for humor or on-topic-ness so that people can (say) still be funny every once in a while without directly contributing to the current discussion per se.
(Sorry that was so long. It was something I had been thinking about for awhile.)
I disagree, because I see these factors as necessarily closely connected, in any person's mind. I rate not quality of prose, but quality of communicated idea, as it comes through. If I think that the idea is silly, I rate it down. If the argument moves me, communicating a piece of knowledge that I at least give a chance of changing my understanding of something, then the message was valuable. It doesn't matter whether the context was to imply a conclusion I agree or disagree with, it only matters whether the idea contributes something to my understanding.