Google CEO Eric Schmidt was recently at the Seoul Digital Forum and he was asked to define Web 3.0 by an audience member. After first joking that Web 2.0 is "a marketing term", Schmidt launched into a great definition of Web 3.0. He said that while Web 2.0 was based on Ajax, Web 3.0 will be "applications that are pieced together" - with the characteristics that the apps are relatively small, the data is in the cloud, the apps can run on any device (PC or mobile), the apps are very fast and very customizable, and are distributed virally (social networks, email, etc).

Here is Schmidt's full answer via a YouTube video uploaded by Seokchan (Channy) Yun (via Orli Yakuel):