Capcom has let slip that an official Nintendo 3DS add-on circlepad – the circular joystick on the left side of the console – will be available for purchase in February to coincide with the launch of Resident Evil: Revelations. The dual circlepads will allow for more accurate aiming in many titles and I can definitely see the value, even over the 3DS’s built-in gyroscopic sensors. I’ve found that playing games like Star Fox in 3D is quite difficult because you leave the 3D sweet spot.
Nintendo World has no further info on the pads and there’s no description of the size, cost, or US availability. All I know is that it makes the 3DS look huge.