Rumors are starting to fly fast around the Nikon D4, the long-rumored successor to the excellent D3 and D3s. A detailed (though unconfirmed) spec sheet made the rounds a few weeks ago, and now the often-reliable Nikon Rumors has posted a photo of a Nikon camera that could be the D4, though the grey box covering up the camera's name badge sets off a few alarms. Overall, the purported D4 (pictured above, on the left) looks like it tightens up the D3s design ever so slightly while still retaining all of the camera's myriad ports, buttons, and dials (from the front, at least). It's been over four years since the D3 was announced, and Nikon definitely needs a response to Canon's monstrous 1D X coming this spring. We're expecting to see more of a camera presence in general at this year's CES, and the D4 would certainly turn a lot of heads.