BBC news has an article about Web 2.0 with quotes from Jakob Nielsen, a prominent web usibility expert. Web 2.0 'distracts good design'
I agree with some of his statements and find the statistics (from unnamed sources) interesting. Only about 1% of users to a site regularly contribute, 9% are occasional contributers and about 90% are just lurkers. That 90% is the key. The biggest question is why aren't they contributing? Are they finding what they need (in which case his concerns about usability are groundless) or are they dissastisfied and look elsewhere?
My favorite line in the article is: "Mr Nielsen also questioned championing teenage use of the web as a harbinger of what people will continue to do when they were older. " I think Mr. Nielsen is saying that once these teenagers become adults they will turn into the rest of us (old fogies like me). As he is not a teenager himself, how can he predict how that generation will change as they age? But I do agree with him.