No, this isn't a blog about the borg. Recently, I ran across an article or two on how products such as delver and twine use social networking APIs and semantic web standards to make search results more intelligent. The idea here is that you pick friends based on what you have in common with them. In which case, it stands to reason that what they think as relevant is a reasonable determinant for what you think is relevant.
This is an offshoot on what is more commonly known as collective intelligence. I first ran across this on the web with the google search engine which capitalizes on the science of predictive markets to provide those miraculously relevant search results at the top of the screen. Books such as the Cluetrain Manifesto and Wikinomics predict and expound on the power and inevitability of collective intelligence and the web, where physical proximity has no affect on cost, as a most excellent way of catalyzing collective intelligence.
April 28 Update: I ran across an article recently called Gin, Television, and Social Surplus that presented a different and interesting take on collective intelligence. The author based this on a speech that he gave at a recent conference on Web 2.0 technology and cultural impact. His upshot it this. One place to go looking for collective intelligence is to siphon off a little bit of the enormous amount of time that people spend watching television.