Canon filed a patent 2011-107255 in Japan for a mount adapter with a built-in aperture. The adapter will have means of communication between the camera and the lens. The aperture in the adapter can be controlled electronically. The camera body on the diagram resembles some kind of a mirrorless solution.
Canon has filed other patents for lens adapters where the the target camera was described as “new type of single lens reflex camera is not provided with a quick return mirror”.
In a recent interview, Canon mentioned that they are considering releasing a small mirrorless camera next year.