Barbasi’s book Linked has been called revolutionary in the way it treats networks, but when considering Web 2.0 does it not go far enough?

The NYT article ‘Folksonomy’ Carries Classifieds Beyond SWF and ‘For Sale’ led me to the 43things site I mentioned in my last entry. This article describes 3 specific sites in an attempt to illustrate how “networking sites” are no longer about simple networks of friends:

Networking sites on the Web started as online personal ads, and most are still built around the desire to meet people. But there is a new, rapidly growing generation of networking sites built around purposes, not people.
These sites connect people by their interests and goals. Three such sites are del.icio.us, which lets users bookmark Web sites and share the bookmarks with others; 43things.com, which loosely connects users with shared goals like learning to play the guitar; and PledgeBank.com, a London-based nonprofit site that brings users together to participate in civic actions, like starting a political group or giving blood.

I don’t think I agree with the claim that networking sites on the web started as personal ads– I always saw Friendster as a new way to connect with old friends, not necessarily a way to meet new people. But I do agree that these network-building sites are evolving beyond simple person-to-person networks. In the same article they describe del.icio.us:

Networking was not the main focus of the site’s design … but evolved out of shared activity. Each bookmark is “tagged,” or filed under a term of the user’s choice; through tags, users work together to categorize the Web, and it is in that context that a network forms. Users meet on del.icio.us in their natural Web environment: the act of finding information they care about.

We all tag in similar ways: I’m sure I wouldn’t be the only one to tag our class blog with “social software” or “web 2.0″. If we tag in similar ways, and common tags are linked, then the act of tagging becomes a shared activity. It creates a layer of connectedness for those users doing the tagging.

Flickr is similar in the way you can tag photos, and through common tags people become linked. Flickr also has the traditional friends and contacts list, connecting you to other users in the same way Friendster does. So in effect Flickr has built-in 2 layers of possible connectedness.

And what about other sites like 43things (connecting common goals) or CiteULike (common academic papers) or even blogs and trackbacks? Each of these, along with Friendster, Flickr, and delicious, are comprised of their own networks, with their own highly connected hubs and other lesser connected nodes.

We can visualize and analyze each of them individually in the way Barbasi describes in Linked, but they overlap. They are overlapping and as a result networks are linked to networks, in a multi-dimensional mesh that has the effect of shortening the distances between nodes.

Are multiple linked networks something that deserve further attention, beyond the inquiry in Linked? Or once connected to each other should these networks be thought of simply as a larger, single network?