Further investigation needed. Definately.
“Teoma’s underlying technology is an extension of the HITS algorithm developed by researchers at IBM several years ago. In a nutshell, the search engine goes beyond traditional keyword and text analysis and seeks out “hubs” and “authorities” related to your query terms — a “social network” of related content that forms a “community” about the topic.
The cool thing about Teoma is that its community-seeking behavior is both query-specific, and happens in real time. “Whenever you type in a query, we’re actually looking for the communities after you type the query,” said Paul Gardi, Teoma’s Vice President of Search. “We’re using a method called dynamic rank, because there’s a lot of information you can learn about that page by its friends.”
Teoma’s approach differs from Google’s, which uses a similar, but more static ranking system. It’s also unlike the approach taken by Northern Light and other engines that classify web pages based on pre-defined categories.
“We’re going into the communities, finding the link structure of the community using text structure as well,” said Gardi.”
Petafloptimism 
[jumbled thought warning – apologies]
something about shirky’s article doesn’t make sense to me. whilst he’s surely right to point out the intrinsic diff. between communities and audiences, his point that communities are essentially ‘throttled’ by the wiring of the human brain feels like it should only apply in the most ‘human-like’ of interactions (chat, mailing-list discussion, etc.) … which is an important point in itself, but the ‘weblog as middleware’ debate feels already slightly removed from this …
the teoma link (which i guess matt’s implicitly adding to contextualise shirky?) is interesting as it describes how a system like teoma understands a community of information – which may not be limited by the wiring of the human brain at all. i kept reading shirky and thinking “but what about emergence, weblogs as feedback loops etc.”, but was unable to properly connect that body of thought with shirky’s thesis. this analogy of teoma’s may be interesting, as its processing of community may not be limited in the same way a brain’s is (ridiculous as it is to describe the brain as limited!). of course, ultimately we still have to parse the results from teoma – but maybe teoma’s ability to comprehend communities with N connections (where N is a very large number as they used to say in school) may add yet more complexity to the already blurred and transient boundaries between audience and community.