After I posted my Map of the Web 2.0 World I got a lot of feedback from people saying that they thought it was interesting but that I had missed a lot categories about what Web 2.0 is.
In my mind the most key aspect of Web 2.0 is that data and functionality are easily shared. Integrating data is much easier than before and that is allowing that information to be used in ways never thought of by the original creators.
Functionality is also much easier to integrate than before. We are now seeing a proliferation of mash ups and examples of APIs being used that we haven't seen before.
On this point I think that there are many companies which are assumed to be Web 2.0 companies just because they are using the latest technologies. I strongly disagree with this. I don't think that your company is a Web 2.0 company just because it uses AJAX. The thing about Google Maps that makes it a great example of Web 2.0 is that it allows other people to go ahead and use the functionality not that there is a whizzy new interface. There will always be whizzy new interfaces, Google Earth was a neat interface where you could zoom around and look at things in ways that you couldn't before but I wouldn't call that Web 2.0.
That is really the motivation behind the Map of the Web 2.0 World that I put up. Web 1.0 is all about data silos and putting up your own database, Web 2.0 is all about sharing the data nad aggregating for your users.