Call of Duty: Modern Warfare 3 multiplayer and Spec Ops Survival mode, as well as Call of Duty: Black Ops' King of the Hill and Zombie modes. Outside, paintballers are playing on real-life replicas of MW2's The Pit and the Scrapyard multiplayer map, and grabbing grub from a full-size replica of a Burgertown franchise.
You can see all the action in the gallery below. Later on today, Activision is holding a few panels, talking about both clan support in the new Call of Duty Elite service, as well as voice acting in the series as a whole. The Dropkick Murphys are playing a closing concert this evening, and there's another whole day of activities and sessions going on tomorrow.
Stay tuned -- we'll have more coverage from the show on both days (minus, of course, the $150 cover charge).