I really enjoyed this book - it's far less bombastic than WikiNomics and raises a number of important 'calming factors' surrounding the areas of collaborative technology. In essence he says it's important, and will be dramatically important for a small number of fields and industries, and less important but still influential in more. However, the book makes a number of fairly bizarre points based on what I feel is a misunderstanding of some of the concepts covered. The biggest example of this is the three-four page treatment he does on World of Wacraft in which he talks about in terms of mass collaboration on content development - in this respect, he may be getting it confused with Second Life, but the argument he makes in favour of this interpretation is entirely in the context of WoW. I feel this is a poorly considered argument for one reason - there is nothing new in Warcraft that hasn't been in all social gaming. They're all about collaborating to have fun, but they do not involve content generation. Warcraft is a large scale content-consumption platform, but it's not a content generator.
On the other hand, there is a thriving 'cottage industry' of add-on development which does involve considerable collaboration, but that's not the argument he makes.
On the whole though, a strong book that would make a good introduction to anyone wondering what all this wiki/collaboration stuff was about and why it mattered.