I just created a new section in my handbook called Recommended Links. Before, I only had one link, Troy Angrignon's post on the mental evolution that people go through from Web 1.0 to Web 2.0.
I've just added a second: Danah Boyd's post on Why Web 2.0 matters, where she goes through more of the social and business changes taken place that are being aided/accelerated by technology.
And yes, there is What is Web 2.0 as well. This is my corner where I can send people a single link and tell them to read the posts linked there, then come back and talk.