It looks sort of like a projectile to me, maybe with the propulsion coming from the round bits on the left side of the image? One might interpret the PHOT1093 marking to indicate it being a photon torpedo. Of course with Marcus involved, the obvious conclusion to jump to is that it's a new version of the Genesis Device. I rather hope it's something more original than that though. Any guesses?
UPDATE: Empire Online has also posted a couple of new images from Into Darkness, both appear to be from the Qo'noS section of the film, including a really nice look at new Klingon disruptor prop: