Just what is Web 2.0 - the phenomenon sweeping the Internet? Chris and Gihan give you the big picture overview - explaining the principles of Web 2.0 and how to change your thinking to take advantage of it.
Wikipedia has an introduction to Web 2.0.
Download "An Introduction to Web 2.0", a special report from the Change This Web site. This report gives you an excellent introduction to Web 2.0 from a business perspective.