There's an innocent explanation: His digital-music startup, Project Playlist, which recently scored a deal with EMI, has its offices in a downtown Palo Alto building shared with Facebook. But that doesn't explain why our tipster, who spotted Van Natta twice today, saw him walking from that building to another Facebook office. Could be a coincidence. Or it could be that Van Natta, who remains close to Facebook executives like Chamath Palihapitiya and Dan Rose, is up to something.

In 2007, at the height of Facebook buzz, the startup was red-hot, a recruiting machine which could poach employees from a then-untouchable Google. Since then — and especially since Sandberg signed on — the company has been more known for the employees it's lost than the star hires it's made.

Qi Lu, formerly one of Yahoo's brightest tech executives, accepted the CTO job at Facebook, and then reneged on his agreement and joined Microsoft as its online chief instead. Pankaj Gupta, an algorithms expert heavily courted by Facebook, went to Twitter. And we hear there may be more defections in the business-development department, where Dan Rose's incompetent management is steadily driving talent away. We hear Richard Cooperstein, who gave up a senior vice president job at Disney to join Facebook as a director, is thinking about leaving.

The many people who passed on Facebook job offers must surely be congratulating themselves on their decisions. If they hadn't they'd now be filling out "awesomeness" surveys.

A tipster tells us:

[Ask] for results of the employee satisfaction/morale survey called the "awesomeness survey." You'll find that the results were not so awesome, in fact... Very not awesome.

Awww, buck up little Facebookers! Tell us what's got you so down.

And Sheryl? Before you haul off and shoot us, remember that violence never solved anything. Here's a good-will gift: some Successories posters you might want to put up around the office before the next "awesomeness" survey.

"Every day, you need to create a to-do list," Rose told Kendall. "You put the items you need to do on the list, and you need to review the list with me every day. As you do them, you need to cross them off." Kendall's retort, which he delivered not to Rose but to friends within and without Facebook: "No shit Sherlock, I didn't get to where I am today without knowing how to manage a to-do list!" What's odd about this rumor: Rose doesn't have a reputation as a micromanager, and the two both worked at Amazon.com before joining Facebook. They put on a convincing buddy act for the New York Times recently, too. Anyone care to play Encyclopedia Brown and help piece together this puzzle? My only conclusion: The best algorithms can't predict what will break a friendship.

(Photo by Chris Pan)