Marc Andreessen has started blogging and out comes a series of great posts, especially this one about how there’s no such thing as web 2.0. He calls it a trend:
What happens when startups start getting referred to as "Web 2.0
startups" — or for that matter, "B2B startups" or "mobile startups" or
"pen computing startups" — or as being in the Web 2.0/B2B/mobile/pen
computing "space" — is that trends are getting mistaken for markets
You can’t build a company based on a trend.