I just had to post this:
http://www.readwriteweb.com/archives/eric_schmidt_defines_web_30.php
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).
There’s a video on this blog post worth taking a look at.