Today's post is
The Old Web = Ten Million Catalogs (part of his The Social Web: What's The New Web Worth series) which looks back at the past ten years of the Web to draw out the distinction of what the new Social Web has become.
These services are based on a catalog metaphor, where sellers can offer goods or services, and buyers (generally consumers) can find them and acquire them. The volume and low overhead of online services hollowed out the markets in most areas thet they touched, for example, sideswiping brick-and-mortar bookstores, blowing up the travel agent business, and strongly cratering the head hunter marketplace.
I like where this is going - pointing out a 'catalog metaphor' for Web services helps me describe to people how my current company isn't just a directory of people - it's a way to add a social dimension to the Web, centered on people not pages.