BusinessWeek columnist Sarah Lacy has more details on Slide's new funding round: Max Levchin's Web widget factory is now valued at $550 million, after raising funds from the likes of Fidelity Investments and T. Rowe Price. While the company is mum on IPO prospects, such big institutional investors typically come in during a so-called "mezzanine" round — a company's final private financing before a public stock offering.

Lacy, citing an internal Slide presentation, says the company ranked ninth in reach on the Web, after, and now has 150 million users for its MySpace slide shows, Facebook apps, and other Web applets. That's an increase of 142 percent from a year ago, when Slide's valuation was reportedly a mere $80 million. A nice trick: Just double your user base, but see your valuation grow sevenfold.