If time flies when you're having fun, the inverse is true as well. Ex-Googler Sheryl Sandberg joined Facebook as COO only two weeks ago and "It feels like she's been here six months already," one Facebook exec told the Wall Street Journal. Sandberg has introduced employee performance reviews, new recruitment procedures, and management-training programs. Suddenly, the place sounds a lot less fun for its 550 employees than it did when Lesley Stahl from 60 Minutes visited Mark Zuckerberg at the offices last fall. It may be good news for Facebook's investors, though.

Last fall wasn't a particularly good time for the company. Facebook Beacon made all the headlines, but stories of Facebook employees snooping around and defacing user profiles made it clear the company needed an adult in charge. Now it has one. Sandberg, who calls herself a "tough-love leader," knows her new corporate mentality will kill what some Facebook employees love about the company. Minions under her charge at Google certainly chafed under her leadership.

But this isn't about the whiners in the engineering quad. Sandberg is trying to make them rich, not happy. "Scaling up is hard and it's not as much fun not to know everyone you work with," she told employees, many of whom themselves own shares in the company. "But if we get to work on things that affect hundreds of millions of people instead of tens of millions, that's a trade-off worth making."