This seems to be the best one for my purposes. I'll be referencing the metaphor in an upcoming top level post, and I wanted a) to be able to familiarize people with the concept, b) do so in a way that maximized the chance that a new reader perusing Less Wrong would hyperlink their way to important Less Wrong concepts and fall in love with the site.
(I'm a little on the fence about what I think about hyperlinks. I think they're annoying if overused and in this case it's probably not strictly necessary, but it did occur to me that, frustrating as they were, the massive hyperlink chain that I fell into was important to plunging me into the site)
Manfred's post was the one I found that seemed close but not quite right. Compared to Hariants, I think it's the best one to use for purpose B.
Orson Scott Card actually wrote quite a fun story that basically predicted the wikipedia effect in 1989. And it inspired his character to make a major scientific breakthrough, so hey, maybe he was right about that too. Hyperlink away, I say!
I've searched a few related terms in Less Wrong, and I can't seem to find the article I'm looking for. It's an Eliezer post that describes a process of drawing a map of a city, and how you can't do it with the blinds closed, you have to actually go out and look at the city.
I've found the wiki definition page, and I've found articles that look like they refer to the original in the way Eliezer often refers to his earlier metaphors, but I could have sworn there was a shortish article that specifically introduced it.
(Is it possible that my map is simply wrong and the original parable was only a small portion of a larger post?)