Nikon patents in Japan have been decoded at NikonRumors.com and relate to (you guessed it) a mirrorless camera system. The system is not APS-C based like the Sony NEX or Samsung NX10 and Nikon are not joining Micro 4/3rd’s. Instead they are set to produce the smallest possible interchangeable lens camera, with 49mm lens barrels (think filter thread size of the Olympus EP1 kit lens).