O'Reilly Media has released a new book on Web 2.0. Called Web 2.0 Architectures, this book should help you understand better the inner workings of Web 2.0 from a technology perspective and how some online services today have been successful with this model.
If you are looking to understand Web 2.0 from a marketing perspective, this may not be the book for you. But if you are a web architect, business analyst or someone who wants to build your own Web 2.0 website or solution, there is bound to be some information in this book to get you started.
I'd personally also like to re-thank Mark Little, Simon St. Laurent and Matt MacKenzie for their work on this book too. While not reflected in the credits, these three had an immense impact on the thinking and research that led to this book. Last but certainly not least, Tim O'Reilly himself deserves a lot of credit for challenging us on how we think about patterns and interpret Web 2.0. Again, while not reflected in the book, all of these people were instrumental in shaping this work.