At Steam Dev Days today, Jeff Bellinghausen with Valve Software said the company is slated to release an update that will expand Steam Controller configurability options to the PlayStation 4's DualShock 4 controller.
Co-presenter Lars Doucet, developer of Defenders Quest, explained, Believe it or not, when you use the PS4 Controller through the Steam API, its exactly the same as a Steam Controller. You make the exact same API calls, you only get actions, not inputs, and the Steam API takes care of everything.
This is a cool addition. I hope Wii U Gamepad and Xbox One controller are next.