After the tech bubble burst in 2000, Scott McNealy, CEO of Sun Microsystems commented, referring to the improbable valuation of Sun during the bubble, “Do you realize how ridiculous those basic assumptions are? You don’t need any transparency. You don’t need any footnotes. What were you thinking?”
I just saw this nice little piece of analysis on Google, which answers the same question. You are, apparently, thinking that Google’s revenue will be 5-10% of US GDP in ten years. That’s what the current share price implies.
Financial Reality 