Updated with comments from Matt Cohler

Matt Cohler, Facebook‘s vice president of product management, is leaving the social networking company to become a general partner at Silicon Valley venture firm Benchmark Capital.

This announcement follows the departure of Facebook co-founder and Chief Technology Officer Adam D’Angelo last month. Cohler was one of the first five employees hired by Facebook’s founders, and helped oversee the company’s growth, so his departure raises questions about how the company’s culture is changing. As early employees leave and the company brings on new executives, is Facebook (perhaps inevitably) becoming more staid and corporate?

It’s not completely clear why Cohler is leaving; in the press release, he cites “an extraordinary opportunity to build on my experience helping great entrepreneurs and to work side-by-side with some of the best investors, technologists and strategists I have ever known.” I’m scheduled to speak to Cohler later this morning, and I’ll try to get more details then.

He’ll be leaving Facebook in the fall, but will supposedly maintain a relationship with the company.

Obviously, this is a coup for Benchmark — Cohler was also part of the founding team at LinkedIn, the professional networking company which recently raised additional funding at a valuation of more than $1 billion. It’s not bad deal for Cohler, either; he gets to step away from the day-to-day stress of running a startup, join a firm that’s well-known for the scrutiny it gives to potential partners and work with cool new companies.

Benchmark General Partner Steve Spurlock tells me the firm has been pursuing Cohler for a while. After all, Spurlock says, Cohler’s “entrepreneurial record” is impeccable: “With [LinkedIn founder] Reid Hoffman and [Facebook founder] Mark Zuckerberg, he’s two for two there.”

Naturally, Spurlock says Benchmark wants Cohler to continue connecting with the superstar founders and chief executives of the future. At 31, Cohler will be the youngest partner at Benchmark, and his youth should help the firm reach out to younger entrepreneurs — plus, Spurlock says, it means Cohler could have a decades-long career as a VC ahead of him.

Update: Cohler tells me he’ll maintain a formal role as a “special advisor” at Facebook. Exactly what that means isn’t clear yet, since Facebook doesn’t have an advisory board, and Cohler says the details of the position will be worked out this summer.

“I’m leaving the company in capable hands, probably more capable hands than mine,” he says, noting specifically that he’s good friends with new chief operating officer Sheryl Sandberg.

As for why he’s leaving, Cohler argues that his role at both Facebook and LinkedIn has been “building lasting companies — if you look at the job description, it’s pretty much that of a venture capitalist.” Becoming a VC always seemed like a good long-term path, he says, but that plan didn’t become concrete until he was approached by Benchmark.

Cohler adds that the firm’s unusual structure, in which each partner gets equal share of the profits (rather than dividing them based on the hierarchy) was a big draw as well.

At Benchmark, Cohler says he plans to focus on “the entire stack of Internet technology,” including mobile technology. Again, the details haven’t been worked out yet, but, “The joke I’ve been telling people is, ‘I have a feeling it won’t be semiconductors.'”

VentureBeat's mission is to be a digital town square for technical decision-makers to gain knowledge about transformative enterprise technology and transact. Discover our Briefings.