I've long been a fan of Clay Shirky's writings published on the web, and just finally received my copy of his latest published work "Here comes everybody" which collates much of this work into a very nicely packaged tour of the impacts of our new media world on social networks and group behaviour.
My first introduction to Clay's works was his article Ontology is overrated, which is an essay on the transformative power of tags vs categorization. It opened my eyes and quantified something I'd been seeing happen, but unable to express coherently. Highly recommended reading.
His new book covers the transformative power of our newly acquired ability to form groups of various sizes and types based on the tools that are now ubiquitous due to the various online tools that eliminate much of the friction of creating and assembling groups. The book is full of fascinating examples that, while anecdotal, clearly demonstrate that we are starting to move into a different era of communications.
This is a must read for anyone interested in the psychology of groups and the impact that ubiquitous social tools have on them.
He's not sitting still on these subjects, and his latest talk concerning what he calls the cognitive surplus of society is making the rounds and is well worth reserving 15 minutes to watch.