Valve's third SteamOS announcement this Friday looks set to be for a new controller.
Following the unveiling of its Steam Machine living room PCs overnight, Valve has made reference to a controller in its Steam Machines Beta Test Agreement.
"Valve Corporation ("Valve", "We", "Us" or "Our") has developed and produced prototypes of entertainment system hardware and software, including a set-top box running custom software and a game controller (collectively: "Beta Products")," the document reads.
While it's possible the controller is for testing purposes only, Gabe Newell confirmed in January that the company is developing a biometric game controller.
"I think you'll see controllers coming from us that use a lot of biometric data," Newell told The Verge in January.
Valve's Steam Machines will run the newly announced SteamOS. Valve will ship 300 high-performance prototypes of the Steam Machine to beta testers later this year.