Replacing Palihapitiya, who will now focus on product, is newly hired VP of Communications and Public Policy Elliot Schrage, who recently joined Facebook from Google.

Why replace an engineer with a lawyer as head of a developer-facing platform? From what we hear, the thinking is that the policy side of Facebook Platform is becoming more important than ever. For most of the last year Facebook dealt with renegade app developers via algorithmically enforced rules that determined how “viral” they could go. But more recently they’ve been making more general, subjective calls on how applications can behave. Creating and enforcing these policies is the job of a “diplomat,” says our source, and Schrage is uniquely qualified for the job. Presumably Schrage will have plenty of right hand guys to figure out all that technical stuff that makes up the platform.

This also shows the continued weeding out and neutering of the old guard at Facebook. Palihaptiya at one time ran about a third of the company, including product, marketing and the platform. He’ll now focus mostly on product, but at least he’s staying. Peers of his like Matt Cohler, Owen Van Natta, and Adam D’Angelo all left the company this year as Schrage and new COO Sheryl Sandberg came on board from Google.

There are more changes on the way.

Crunch Network: MobileCrunch Mobile Gadgets and Applications, Delivered Daily.