Having read some of the links about Web 2 I agree that the difference really is in the way people are using it rather than that it is a whole new thing. I do have some reservations about my students using some of the feedback and discussions they find as authoritive. It's the same problem that I have with Wikipedia (the start of the Web 2 technologies in practice??) Even the senior students go straight to it and don't question what they find. My job is increasingly getting them to question what they find and confirm it from other reputable sources.
The other side of Web 2 that I do like is the interaction between students that it encourages. The discussions and sharing are great. For those of you who aren't familiar with the "book raps" idea - this was an early step towards getting students to share opinions and ideas online.