Zipper Interactive's 256-player MAG: Massive Action Game. We say "actual" because it was clear to anyone with eyes that Sony had pulled another Killzone 2 with the MAG video debuted during its pre-E3 press conference. In other words, it was all pre-rendered.
MAG senior producer Rade Stojsavljevic posted the shot to the official PlayStation blog, calling it "a sneak peak from one of [Zipper's] internal play sessions." Stojsavljevic also said that the dev has used its experience working in online games with the SOCOM franchise to create an entirely new server architecture for MAG capable of supporting its, well, massive amount of players.