Since launching its first native iPhone app in 2008, Facebook has taken an all-in-one approach to building mobile apps with most major features of the site accessible in a single application.

But it looks like that may be about to change with leaked photos of a forthcoming photo-sharing app obtained by TechCrunch, which would push the social network into a competitive, but nascent field of apps like Instagram, PicPlz, Path and Color.

Designing apps around a feature or single behavior represents a sea change in thinking for the company. It’s a recognition that making users do two clicks into the app to access messages, chat or photos introduces too much friction and that apps built around a pared-down set of actions done in 30 seconds or less perform the best. This contrasts with what the company has done in the last few years in trying to put as much of the website’s functionality into its mobile apps as possible.

Building standalone, feature-centered apps isn’t unanticipated. When Facebook acquired group messaging app Beluga earlier this year, it raised speculation that the company might also build a standalone messaging or chat app.

Upstarts have also captured sharing behavior that Facebook might think it should rightfully own. By honing the action of sharing a photo down to as little as snapping an image, choosing a filter then posting, Instagram has quickly amassed close to 100 million photos and 5 million users since its launch nine months ago.

We wouldn’t be surprised if this photo-sharing app is the first in a few experiments in this new direction. Lastly, this shows how Facebook has continued to be a fast-follower on concepts with traction like location-sharing and group deals.