Found on the SteamDB twitter page. It seems Valve has made another revision to their Steam Machines controller design. There are two new redesign implementations the first is a left thumbstick has been added. Then on the right of the thumb stick are face buttons you would find on a traditional PlayStation or Xbox controller.
New Desgin
This is reportedly the third revision Valve has conduct to their steam controller. The Steam controller will be utilized for playing on Valve’s Steam Machines. The Steam Machines are being built in coordination with Valve and Gaming PC manufacturers to allow for affordable gaming PC’s rigs with some competing with consoles in price.
Old Model Design
There are Steam Machines that can be fully upgraded which allows for more power, but they also come at a price similar to a regular gaming PC you would build with high end tech. To set the Steam Machines apart Valve has created a custom OS title “SteamOS” for the machines that resembles somewhat of a consoles OS. Alienware is prepping their release of the Alienware Alpha Console which will ship this holiday season of 2014 at a price of $549. You can see what this system is all about here.