This is a little clip that covers the camera on your iMac when you don't want to be spied upon. The microphone is not obstructed. It clips on easily and can easily be removed or just slid to the side. The cover fits generation 6 iMac machines.
Isn't there a small led light on their as well which turns on when the webcam is accessed? That way you don't have to be paranoid about the webcam watching you whilst you ain't using it. Oh well... it kinda seems over the top to me personally ... although it's a perfect example of why 3D printing is so awesome (as in, there would never be a market for this otherwise ).