Miller calls it the Cantroller. It's not an empty beer can that has been modified into a controller with appropriate electronics. It's actually filled with beer that is completely drinkable--at least to the extent that Miller Lite can be called drinkable. Miller produced 200 of them for the E3 consumer electronics show. They can be won by beating a champion player at the show. Fox News reports:
The game controls are on the other side of the can, all arranged with flat membrane buttons that don't affect the profile of the can itself. It's as simple as you can get, just a direction pad and four face buttons in a Nintendo A/B/X/Y configuration, with Start and Select buttons. The direction pad and Start and Select buttons are all completely flat and click inwards, while the face buttons are slightly raised. The battery pack and Bluetooth transmitter is mounted on the bottom of the can, with a small ribbon cable running to the membrane panel with the controls.
-via Dave Barry