I have almost the same problem, but it's Shift that is stuck so I won't be helped by the standard system settings in os x.
I actually (in some type of anger) tried cutting the silicone nipple off myself, but it's still pressed. Can't really tell whether it's the L or R shift. I decided it was the left because it didn't work at all. The right one responds.
Nothing have helped so far, and I tried installing keyremap4macbook but making changes there makes no difference what so ever, it's still active(?)
The biggest problem with having the shift constantly pressed is that on reboot, the computer chooses the internal keyboard instead of the external, which works just fine when the computer is on. But starting the computer with shift pressed turns it on in safe mode, which is horrible. No sound, no watching video etc.