Mine isn't, I run an OSS system that lets me verify that the camera is indeed off. It also works disconnected without sabotaging the functionality and software that doesn't require a connection. The camera led is impossible to disable without hardware tampering, too. And I can even tape it and it will continue working.
The XBOX PRISM is a different creature altogether, and a very worrisome precedent precisely because we already have smartphones and tablets that could potentially follow that path.