What will Google be like without Marissa Mayer, the glamour nerd whose goofy laugh so neatly captures the search engine's adolescent awkwardness? We'll know soon. We hear the company's 19th employee is planning her goodbye.

Top Googlers, overheard at a holiday party, chattered about Mayer's departure as a matter of if, not when. And in some ways, it's surprising she's stayed as long as she has.

First of all, she's wealthy. That "19th employee" bit is code, within Silicon Valley, for "rich"; the earlier an employee joins a startup which succeeds, the more money they make. With Google, which is still worth $96 billion after its stock tumble, that translates into hundreds of millions of dollars for Mayer, who owns a penthouse apartment in San Francisco's Four Seasons, another home in outrageously pricey Palo Alto, and a large (if questionably tasteful) art collection, including original glass sculptures by Dale Chihuly. A couture hound, she once paid $60,000 for a lunch with Oscar de la Renta, and she owns part of I Dream of Cake, a "cake gallery" in North Beach, as a way of indulging her pastry fetish.

So she's already made her money. And her career? Mayer, who joined Google in 1999 straight out of Stanford's graduate computer-science department, rose quickly through the ranks. A stint dating Google cofounder Larry Page surely didn't hurt her chances, but she won promotions first to director and then to vice president mostly by dint of a schedule of robotic overwork and an obsession with keeping the search engine's homepage sparse and free of clutter. Her looks — blonde, Midwestern, unusually attractive for Silicon Valley — helped her win magazine covers. And she won fans among Google's tight-knit top management, even as underlings groaned about her scattered, arbitrary management style.

But the lack of turnover in Google's excuive ranks has hurt her chances of rising farther. Jonathan Rosenberg, a six-year veteran of Google who's close to its founders and a regular on its quarterly earnings calls with Wall Street analysts, would be hard to displace. While Mayer photographs well, she's an awkward public speaker — that awful, offputting giggle! And really, she already runs the world's most successful search engine, which continues to steal share from well-funded rivals. What else could she do at Google to match that?

It's a good time to leave: Mayer just got engaged to Zack Bogue, a property manager and lawyer who, importantly, looks good on his fiancée's arm at the San Francisco society events she favors. She'll no doubt be courted by venture capitalists, too, to run companies. But if I had to bet, I'd put my money on her returning to Stanford, where she now teaches computer-science classes in her spare time. Academia is the environment most like the comforting cocoon of Google, where she's spent her entire working life. From a professor, a nerdy laugh is almost expected.