From Bungie.net: "Multiplayer, single player, you name it, folks are playing it. The lab formerly known as the multiplayer lab is now also the single player lab, where folks may go in at just about any time and start playing through a selection of single player Campaign missions.
At this point, they're testing out the new AI and encounters as much as anything else. The graphics range from completely untextured placeholder surfaces, too brilliantly lit and detailed objects. But again, this is a gameplay test, not a graphics one. Lots of folks focus on what technology can do for the appearance of a game - but the 360's prodigious horsepower can also be applied to AI - the behaviors, movements and reactions of computer-controlled characters. That counts for your human allies, but it's more noticeable at this early stage in the behavior of your opponents.
Today, I swear I saw some Grunts do a classic pincer-movement to trap me in a narrow canyon. I was battling um, something bigger than a Grunt, and suddenly, I'm being peppered by a second group of jerks, mostly Grunts, who'd been sent in around my flanks to take me out. Grunts are still grunts though, and once I showed some serious opposition, a couple of them panicked and fled, but they nearly had me and it was quite a shock.
When the single player guys file out (or as is often the case, stay put) then the multiplayer sessions begin in earnest. We were trying out a new multiplayer game type - and it is super fun, yet utterly terrifying at the same time. I have never, ever heard so much frightened screaming during a play test of anything. And plenty of laughing too."