Danah Boyd, apophenia, has taken up the discussion on defining social networking technology. Be sure to check out the comments.
"let's define our terms: what is a "social networking technology"?" by danah boyd.
"In writing Social Network Sites: Definition, History, and Scholarship,Nicole Ellison and I wrote many iterations of the definition of the term "social network sites" and why we chose to use this instead of "social networking sites." For a good 20 versions, we had included this statement:
"Because the term 'networking' emphasizes relationship initiation, often with strangers, it can and has been expanded to refer to any site that allows people to communicate with people that they do not know, including dating sites, chatrooms, community sites, and bulletin boards."