A lot of the main sequences of material (http://wiki.lesswrong.com/wiki/Sequences) there were written by a Hacker News member, Eliezer Yudkowsky. But it's also a great living community (like here), with new stuff constantly being added.
So I've been there a couple of times, mostly via HN, and I had this odd experience of being unable to place the site somewhere in my internal onthology of web communities. Forum? Wiki? Blog? Scifi? Psychology? Religion? Agnostics? Atheists?
I think a reasonable classification of LessWrong would be a forum-blog combination; it's mostly made up of agnostics & atheists, but this is not at all a focus.
The RationalWiki article is reasonably accurate, I think (speaking as someone who hangs around on LessWrong a bit), none of it is obviously untrue, although there is a bit of "undue weight" given to some things (i.e. the some of things mentioned only come up occasionally, especially the more negative things in the Ugly and Bad sections). It is even edited[1] by LessWrong regulars (e.g. David Gerard, Gwern and Ciphergoth), and not at all as vandalism, they all seem to have added both positive and negative material.
http://lesswrong.com/
A lot of the main sequences of material (http://wiki.lesswrong.com/wiki/Sequences) there were written by a Hacker News member, Eliezer Yudkowsky. But it's also a great living community (like here), with new stuff constantly being added.