Social networks form around objects
I have to agree with Russ: Object-centered sociality is much better than the social networking approach of talking about relationships in a void, as Jyri Engeström's post makes clear. It's nice to have theoretical backing for the problems with social networking that I voiced at CSCW, which were brusquely dismissed by a leading academic. You don't have to read every paper ever written on the subject to realize that boiling your relationships across various objects to a single, cross-domain strength indicator is bogus. Social network software could definitely use a theory injection, but it needs to be the right theory.