Diomidis Spinellis (author of the well-known book Code Reading) and Panagiotis Louridas, both of AUEB, published "the collaborative organization of knowledge: why Wikipedia's growth is sustainable" with DOI:10.1145/1378704.1378720 in CACM:51-8 (Aug 2008), http://portal.acm.org/citation.cfm?doid=1378704.1378720
The two researchers, whose project was partially funded by the European Commission, found that before an article is created it usually already has incoming links, in the form of [[red links]]. Most articles get written within a month after the first red link. Furthermore, incoming links increase exponentially until the article is written, thus making the links blue, at which time the increase becomes linear. Articles are usually created by a different Wikipedian than the contributor who inserted the first red link to it.
I infer that Wikipedians use red links as a way to communicate with one another about which articles should be written first. The MediaWiki software also includes the MostWanted special page in which it counts how many incoming red links each article has. Wikipedia also has the [[Wikipedia:Most wanted articles]] page.
I regard the use of the red links for identifying articles most needed to be written as an example of communication through stigmergy in Wikipedia. I am, however, somewhat concerned about whether most Wikipedians prefer to get this information from the articles themselves or from the MostWanted MediaWiki/Wikipedia features, and whether this could affect the stigmergic nature of the communication. I feel that they probably get this information from the articles themselves spontaneously, and in that case it very much looks like stigmergy; but if they get the information from the centralised MostWanted page, is it still stigmergy? I would think yes, albeit the stigmergic nature of the communication may appear to be somewhat more weak than in the other case. What do other subscribers in the wiki-research-l mailing list think?