Interesting article on Web 2.0 Summit:

The bubble question also lurked in the minds of many attendees at the Web 2.0 Summit conference in San Francisco last week. Along with Facebook, search and online advertising juggernaut Google has an even scarier valuation. In Google’s case, Wall Street justifies its market cap of around $209 billion because of what analysts consider is a huge untapped sector of the advertising market that has not yet moved to the Web.