If you are unfamiliar with the buzzword Web 2.0 consider yourself lucky.
If you want to know more this is a good source
If you are a designer and want to grab loose hints from peers without hitting the wall this is a good start.

There is no much critical debate about the focus communities bear in this scenario, subsequent business models, etc and the word has clearly become a meme, pasted everywhere inadvertedly as a marketing tool.

The Wired game comes to mind, sometimes a mere juxtaposition of fresh terms as opposed to old, spent ones. Wikipedia's radical trust in "collective intelligence" opposed to Britannica's academics.

oReilly again:

If an essential part of Web 2.0 is harnessing collective intelligence, turning the web into a kind of global brain, the blogosphere is the equivalent of constant mental chatter in the forebrain, the voice we hear in all of our heads. It may not reflect the deep structure of the brain, which is often unconscious, but is instead the equivalent of conscious thought. And as a reflection of conscious thought and attention, the blogosphere has begun to have a powerful effect.

First, because search engines use link structure to help predict useful pages, bloggers, as the most prolific and timely linkers, have a disproportionate role in shaping search engine results. Second, because the blogging community is so highly self-referential, bloggers paying attention to other bloggers magnifies their visibility and power. The "echo chamber" that critics decry is also an amplifier. [...] If it were merely an amplifier, blogging would be uninteresting. But like Wikipedia, blogging harnesses collective intelligence as a kind of filter.

Implications are profound, interesting and also open to deep misunderstanding. In some cases we may be tempted to paraphrase the recent "Lord of War", excellent script and excellent Nick Cage's act there's a blogger out of every twelve people in the world... the question is how do we get the other eleven

As participation becomes mandatory as an undiscredited value and getting involved is not an option, where value is to be judged, pushed and emphasized, what tools of the trade can we count on but just plain-old mass appeal?

Please see this by Janice Fraser of adaptivepath and a slight rebuttal by jason Kottke here.

The path is thin, as blurred as ever. (see how USPTO indends to use a Wiki here)

But there is always a short novel of enlightenment.
It's venerable Theodore Sturgeon's Need (1960) • [Hugo Award 1961]

Disconnect from your preferred online com·mu·ni·ty and dig it