Semantic Web vs. Web 2.0

Tim O'Reilly offers interesting thoughts on the nature of the "semantic web" and how it differs from "web 2.0" in a recent post on his O'Reilly Radar. He think both terms are often misused, including in a recent Economist article on three web companies (ValuesOfN, Wesabe, and Tripit). While the distinction is probably obvious to a lot of people, I personally have found his discussion helpful, and I imagine most social scientists could as well.