Facebook Inc. co-founder Dustin Moskovitz is leaving the social networking start-up to form another, continuing the recent string of high-level departures.
Moskovitz, 24, founded Facebook with Mark Zuckerberg, its chief executive, while both were students at Harvard.
Moskovitz, who used to oversee engineering, plans to leave Facebook in about a month with Justin Rosenstein, a 25-year-old engineering manager who joined Facebook from Google in June 2007. They are teaming up to build software they hope will be "to your work life what Facebook.com is to your social life," according to Rosenstein's Facebook page.
Moskovitz recruited Rosenstein to Facebook, and the two have worked together in recent months on software for business users. Social media are increasingly gaining traction inside businesses, which are experimenting to see if they can increase productivity and communication.
Rosenstein became well known in Silicon Valley circles for the enthusiastic e-mail he sent shortly after his hire that touted Facebook as the new "it" company "on the cusp of changing the world."
With more than 700 employees, 100-million-plus users and ambitions of becoming a public company, 4-year-old Facebook is no longer the college hangout it once was. Top among the seasoned managers the Palo Alto company has hired to shepherd its next stage of growth is former Google executive Sheryl Sandberg, Facebook's chief operating officer.
The departure of some key Zuckerberg allies from the early days of Facebook has raised eyebrows. At the time Zuckerberg recruited Sandberg, he said he realized that he needed to turn Facebook's soaring popularity into a revenue-making machine and to expand internationally.
"Dustin has always had Facebook's best interest at heart and will always be someone I turn to for advice," Zuckerberg, 24, said in a statement.
Moskovitz and Rosenstein could not be reached for comment. In a note on his Facebook page, Moskovitz reflected on how Facebook has changed the way people connect and on the bittersweet decision to follow a separate path.
"Whether I work here or not, I'll forever bleed Facebook blue," he wrote.