Stigmergy is roughly "communication through leaving cues in the environment" as with chemical trails left by ants.
Yep.
In BiologyAndComputing, SteveBurbeck points out that multi-cell organisms are based on StigmergyStructures?. Essentially, the cells are temporary; bodies aren't just a bundle of living cells, they're a bundle of ephemeral living cells which are connected and communicate stigmergically through the non-living persistent structures (eg. bone) "we're termite mounds" (or corals?) ( (WarpLink) PersonalIdentity )
Burbeck is explicit that things like tagging are examples of stigmergic information transfer. As is wiki. And JonUdell suggests PageRank allows the whole web.
Question :
But then, what communication isn't stigmergic? Writing must be - ie. we leave writing around the environment. It seems like speech shouldn't be. Is there a MediaAndMaterials question lurking here? Eg. that some sorts of communication are "more stigmergic than others" and this can bias the overall system behaviour in certain ways? (Hey, I claim BonusFreakyConnectionPoints for this ... although that was actually prefigured by a link to WatchingAnts already on MediaAndMaterials, amazing!)