I did a 5QQ for Mediate in which I talk about The Hills, BNO News, and Megantereons. Snippet:
Isn't it interesting that Tumblr and FourSquare are NYC's major contributions to social software in the past couple years? I have a theory! They share this commonality: they're both semi-closed networks. To wit: Though wildly successful, both platforms still somehow feel clubby and insidery.
In the long run, it will be interesting to see if this distinct (dare I say New Yorky?) quality is a feature or a bug.
(Before I lived in NYC, I had a name for social software like FourSquare's predecessor, Dodgeball. I called it "NewYorkWare" because those apps seemed specifically made for the hyper-urban. Similarly, Tumblr seems made for the hyper-mediated.)