This is a recent parent application from Sony Computer Entertainment America, that seems to show some sort of break-apart, motion-sensing DualShock 3.
There were murmerings of such a controller back in the summer, but we were unsure as to whether this would ever actually materialise, or what it would look like if it did.
From what we can tell it looks like the gamepad would be made up of two pieces, each of which would feature an "ultrasonic tracking system". This would help recognise 3D inputs.
The best thing about Sony's approach is that it doesn't bear much resemblance to the Wiimote which means the company should avoid any problems from Nintendo.
Whether we'll see this controller ever come to light of course, remains to be seen. But it's certainly interesting to say the least.