This month’s online edition of the Journal of Computer-Mediated Communication has some interesting articles on Social Network Sites.
Check out the fig. 1 graphic “Launch Dates of Major Social Network Sites” from Boyd and Ellison’s “Social Network Sites: Definition, History, and Scholarship”.
And since it is now a subject of scholarly debate, to those who wonder what killed Friendster, the deleting of the fakesters or the scaling problems, I would just like to submit that my cat was never deleted.