In general, I think LessWrong.com would benefit from conspicuous guidelines: a readily-clickable FAQ or User's Guide that describes posting etiquette and relevance criteria, and general mandatey stuff.

I encourage everyone to look at the example of http://MathOverflow.net/, a web community for mathematicians that started with a few graduate students just half a year ago and has grown immensely in size and productivity since then (notably , enjoying regular contributions from Fields Medalist Terrence Tao).

Not only do they have an FAQ, but a clearly distinguished ongoing Meta forum that was used extensively in its early development to analyze site policies:

http://mathoverflow.net/faq http://meta.mathoverflow.net/

If we did discover a cognitive trick for making people collectively reason better, a sentence about it in an FAQ could work wonders.