The definition and factors of Social Networking Sites isn't really anything new for me. I joined my first SNS when I was 12 on KiddoNet, which was a site for kids only. I then got a Myspace in the beginning of High School, and by my senior year, I had replaced Myspace with Facebook.
What was new whats the history. I have never heard of SixDegrees and wasn't aware that it was the first offical SNS. I would agree with the author that it was ahead of its time. It failed rather quickly, but not because the idea and technology behind it was a flop; it just was present in a time before social networking had entered into the spectrum on technological evolution. If SixDegree had come out right before Myspace and Facebook, it would've probably been just as sucessful as these top networking sites today.
It doesn't really surprise me that SNS have become such a global phenomenon. Theres really something for everyone. Its good for work, expanding your social life, finding a date, sharing information, growing popularity, selling, media, etc... the list goes on. The fact that its gone global has in some way connected the world. Its a big step for mankind.