My two favorite quotes:
"Facebook went public at $105 billion and Friday was selling at $87 billion. At either figure, Facebook's valuation is a projection of a revenue model that doesn't yet exist and hasn't even been articulated by the company. Buying shares at these prices is a bet on capitalist incentive eventually to find a way to turn Facebook into gold. But it's no sure thing. An investor who didn't understand this can find the man who cheated him in the mirror."
"[Zuckerberg's] next trick will be to build a bridge between this data and the existing world of ad-supported media that all of us are immersed in every day....It requires of Mr. Zuckerberg a second act of entrepreneurial creation on the order of his first. But a place to start might be finding out who advised Steve Jobs on how to sell the record companies on iTunes. That person probably belongs on the Facebook payroll pronto."