Sebastien Paquet and Phil Pearson have written a paper about Internet Topic Exchange, a service they built that enables weblog posts to be shared among open groups in the form that we call topic channels. After nearly a year of operation, more than 200 topic channels have been created; several of them have been very active and have brought together many participants.
Now, with the discussion a while back about emergence, one might think that this was about the coalescing of knowledge; the growth of collections of text like termite mounds.
For the metaphor to hold, it implies the following about termite biology -- that the instinct that draws termites to move grains of sand into a pile are different from the patterns that cause them to build structures with passageways and rooms dedicated to various purposes. (I don't know this to be true, seems logical, references to relevent genetic ethology welcome).
Topics serve as pheremones -- people are drawn together by the "smell" of a common interest. It takes an entirely different set of skills to shape those interests into shared meanings, to weave the individuals into a group, to build those shared interest into shared artifacts and actions.