This picture has been circulating the BSN and Reddit. It was shown at the end of BioWare's ME3 presentation at Montreal Comic-Con. Not really sure what the red hologram is. It looks a bit like the Collector base. Feel free to speculate on this.
UPDATE We now have a high-res shot of this here. This confirms that the hologram is of a human ship, but who the hell is that with Shepard?
NEW UPDATE In this video producer Mike Gamble talk about how the Omega DLC, saying that Shepard teams up with a "female turian named" something I couldn't make out. That could be our mystery character! He also says it will be released on November 27th, and is gonna be a whopping $15. Hopefully that means it's gonna be way larger in terms on content in order to justify the price. For anybody doubting the legitimacy of the video, I've met Mike Gamble in person. That's him.