Matt MacAllister likes Freebase, a structured data clearinghouse:"In some ways, it seems like the whole Web 2.0 era was merely an incubation period for breakthroughs like Freebase."
Mark Evans: 5 things that could kill Facebook.
Danah Boyd: Facebook is squewing upper-class, MySpace below.. great thoughts

Josh Porter: Facebook and relationship circles, as in how FB helps leverage them.
Sarahpr: Comments on Josh's post--and the uniqueness of each social network (Yeah, maybe...)
Robin Sloan: Snarkmarket is rocking the quotes these days.