Don Tapscott and Anthony D. Williams have written an intriguing, necessary and, in some ways, groundbreaking book, which we recommend to everyone...with some caveats. The authors examine the possibilities of mass collaboration, open-source software and evolutionary business practices. They integrate examples from the arts ("mashups"), scholarship (Wikipedia) and even heavy industry (gold mining) to argue that new forces are reshaping human societies. Some of their examples will be familiar, but others will surprise and educate you. However, the authors are so deeply part of the world they discuss that they may inflate it at times - for instance, making the actions of a few enthusiasts sound as if they already have transformed the Internet - and they sometimes fail to provide definitions or supporting data. Is the "blogosphere," for example, really making members of the younger generation into more critical thinkers? Tapscott and Williams repeatedly dismiss criticisms of their claims or positions without answering them. The result is that the book reads at times like a guidebook, at times like a manifesto and at times like a cheerleading effort for the world the authors desire. It reads, in short, like the Wikipedia they so admire: a valuable, exciting experiment that still contains a few flaws.