Very insightful post by Kevin Marks about why Twitter works.

It is said that an economist is someone who sees something that works in practice and wonders whether it works in theory. Twitter clearly works in practice – and if you want practical advice, watch Laura Fitton's Tech talk at Google, or read her Twitter for Dummies. I've learned a lot from talking to her and others about this phenomenon, and I wanted to write about some theories that help me understand it…

Worth reading in full.