First I read on Bob Congdon's site about Orkut being taken over by Brazilians. There's nothing wrong with Brazilians outnumbering Americans, but they seem a bit too eager to join seemingly random groups: the Brookline Massachusetts group has 75 members, 7 of whom live in Brazil.
Then Adam Greenfield writes up what many have been thinking in Social networking sites: a postmortem:
Let's start with the indisputable fact that they introduce awkward social situations that did not otherwise exist, or were at least far less explicit.
In a few years, we'll all look back on this and laugh...