I thought this was well expressed by Fred Stutzman on his piece Social Network Transitions:
“To generalize, let’s consider two types of social networks: ego-centric and object-centric. An ego-centric social network places the individual as the core of the network experience (Orkut, Facebook, LinkedIn, Friendster) while the object-centric network places a non-ego element at the center of the network. Examples of object-centric networks include Flickr (social object: photograph), Dopplr (social object: travel instance), del.icio.us (social object: hyperlink) and Digg (social object: news item). The characteristics of ego- and object-centric networks are similar, and a human can certainly be considered a social object, but I delineate based on the significant experiential difference.”
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:“As I’ve stated, Facebook and the ego-centric social networks are the outliers in social software. And while its tempting to be the outlier (look, Techcrunch says Facebook is the 5th most valuable internet company ever!), its an ultimately impossible proposition. Object-centric networks, however, offer unlimited potential.”
ceo