Inside Facebook

Paul Buchheit, an early Google employee who coined its “Don’t be evil” motto and created Gmail, is moving on from Facebook to become a partner at startup incubator Y Combinator.

Buchheit joined Facebook in August of last year when the social network acquired his social sharing service FriendFeed. Buchheit confirmed publicly that he was leaving the company on his FriendFeed page.

“It has less to do with Facebook and more to do with me,” Buchheit wrote. “I’m just more excited about helping new entrepreneurs create the next Facebook or Google.”

He also leaves shortly after Facebook initiated a partnership with YCombinator to provide technical and design resources to new social startups.

Facebook said in a statement: “We support Paul Buchheit’s decision to pursue his passion and advise start-ups full-time. While he’ll be missed at Facebook, Paul has already established himself as a respected angel investor and we hope his insights will be helpful to the next generation of Silicon Valley start-ups.”

Facebook typically acquires small companies purely for talent, instead of for their products. As Buchheit leaves, his original Friendfeed co-founder Bret Taylor has moved on to take a high-profile role within Facebook as the company’s chief technology officer.

At least a quarter of FriendFeed’s original employees have left since the company was bought for a reported $50 million last year. Kevin Fox stayed at Facebook for 10 months before leaving and eventually joining Mozilla Labs as principal user experience designer. Another employee Ben Darnell left three months after the acquisition to join Brizzly, which was later bought by AOL.

Buchheit is a much higher-profile departure because of his Google background, because he’s a thought leader in Silicon Valley and an active angel investor. He also leaves as Facebook is possibly preparing to launch its own e-mail service next week in San Francisco.

While at Facebook for more than a year, neither Buchheit nor the company was completely clear about what his title or role at the company was, although he says he made a few changes to the search engine a few days ago. At the same time Buchheit became busier investing and mentoring young founders, and scored some exits with Mint, Remail and Appjet.