So... the longer I think about this Wiki thing, the more it seems like a really good idea - a missing piece falling into place.
Here's my proposal, which I turn over to this, the larger community that suggested the Wiki in the first place:
The Wiki should consist mainly of short concept introductions plus links to longer posts, rather than original writing. Original writing goes in a post on Less Wrong, which may get voted up and down, or commented on; and this post should reference previous work by linking to the Wiki rather than other posts, to the extent that the concepts referred to can be given short summaries. The intent is to set up a resonance that bounces back and forth between the Wiki (short concept summaries that can be read standalone, and links to more info for in-depth exploration) and the posts (which make the actual arguments and do the actual analyses).
My role model here is TV Tropes, which manages to be, shall we say, really explorable, because of the resonance between the tropes, and the shows/events in which those tropes occur, and the other tropes that occur in those shows/events. And furthermore, you know that the trope explanation itself will be a short bite of joy, and that reading the further references is optional.
There would be exceptions to the "no original research" rule for projects that were multi-editor and not easily prosecuted through comments - for example, a project to make a list of all posts with one-sentence summaries in chronological order.
There are also obvious exceptions to the "link to the wiki" rule, such as for any case where it really was futile to reference anything except the complete argument; or where you wanted to talk about part of the argument, rather than the general concept argued; or when you wanted to talk about a conversational event that happened in a particular post.
I would suggest that the general format of a Wiki entry be a short summary / definition (that can maybe gloss or list some of the arguments if there's room, or even give the argument if it can be put really briefly), with the body of this being no more than a screenful as a general rule. Then links to posts, with descriptions (for each post) of why that post is relevant or what it has to say - probably one or two sentences, as a rule. Then references to outside posts on the same topic - although if the best reference is an outside discussion, that could come first.
Summaries of whole sequences could also go on the Wiki - since it seems more like static descriptive content, rather than debatable analysis and argument, which is how the wiki/blog dichotomy is starting to shape up in my mind.
Given unlimited development resources we'd want to integrate the two userbases, have a karma requirement to edit the Wiki, and such things, but we don't have much development resources (whines for Python volunteers again). But I would still like to see a list of recent edits and/or active pages in the Less Wrong blog sidebar, and a list of recent blog posts and recent comments in the Wiki sidebar. Of course the first priority is getting the Wiki set up on Less Wrong at all, rather than the current foreign host - I'm told this is in In Progress.
Once my old posts are imported from Overcoming Bias, it would be nice if someone went through them and changed the links to posts (that reference concepts per se, rather than conversational events or parts of arguments) to links to the Wiki, creating appropriate pages and concept summaries as necessary. That is, it would be nice if I didn't have to do this myself. Anyone interested in volunteering, leave a comment - it'd be nice if you had some comments to your name, by which to judge your writing skills, and perhaps some karma. This is a large job - though 10 posts a day would get it done in two months - so don't step up if you don't have the time. It does seem like the sort of thing that should definitely get done by someone who is not me.
I've already seen at least one person call Overcoming Bias "a bigger, and far more productive, time sink than Wikipedia or even TV Tropes". Done right, it really could be more addictive than TV Tropes, for the intellectually curious, because it would seem (and be!) more productive; when you browse TV Tropes it feels like you're wasting time.
I suppose I should feel slightly nervous about this, but it still seems like something that ought to be done if feasible, even though it sounds a bit scary - and I hope I'm not just saying that because I'm tempted to break out into mad scientist laughter.
Right. Both blog and wiki should be outward-looking, using whatever is the best for their purposes. At the same time, they play different roles: the blog is for publication of new research in the relevant area, and the wiki is authoritative reference of relevant concepts. The wiki may be a useful place to link to from the blog, by virtue of being centered on the same area of investigation as the blog, but other than that it competes with the rest of the info in the world. Likewise, the blog may be a useful place to reference in the wiki articles, but it also competes with info in the rest of the world, with standard scientific publications, with Wikipedia, etc.