Today (14th May 2007) Scott Abel, "The Content Wrangler", is giving a presentation at the 54th STC Conference on Web 2.0, whatever that may be, and its impact on technical communication.
I admire Scott, who is an expert in his field, and a great speaker. I just happen to think that the phrase "Web 2.0" is marketing hype, rather than a meaningful description of anything. It's well known that Tim Berners-Lee himself has said much the same thing.
I recently read a report published in February 2007 by JISC, "What is Web 2.0", in which the argument on whether there is such a thing as Web 2.0 is characterised as "a tale of two Tims", one of whom being Berners-Lee, and the other being Tim O'Reilly, founder of the high-tech publishing company that bears his name, and a great populariser of the term "Web 2.0".