Valve has already sent out 300 beta Steam Machine all of which came with a beta version of their Steam Controller. While the beta controllers did not have a touchscreen after testing by the beta users the controller is going under some changes and is ditching the touchscreen idea and adding more buttons.
The new mock up of the controller is shown above and you can see that there are now 4 sets of buttons on each side added. They are laid out in the classic D-pad style. This of course is only a mock up, but it seems this will be the direction Valve is going forward with.