Yesterday, I was playing a four player game of Left 4 Dead, a co-op zombie shooter. I was fairly surprised when I turned around, and found kt watching over my shoulder. Was even more surprised when she watched for the entire time she was exercising on the torture machine. I was knocked on my ass when she said that she'd like to play. Unfortunately, that requires picking up a copy on the 360. Fortunately, that's something I was looking to do anyway.
What I've noticed is that there aren't a lot of co-op role playing games. Of course, turn-based games are a bit less interesting in co-op, because the nature of them means that it's just as easy for one person to control as for two people. Action RPGs have more promise, but there still aren't very many of them out there. I've got high hopes for the new Final Fantasy Crystal Chronicles game on the Wii, but other than that, there's not too much coming down the pipe.
I'm very glad to see much more interest from developers in pushing co-op as an integral gameplay feature. Shared play experiences, where a group has to work together and can celebrate a communal victory or defeat, have the potential to be much more lasting than one person killing the hell out of his buddies.
Here's an example from yesterday. Two of the guys in the game are extremely good at it, two of us weren't. In a competitive game, being on the lower side of that equasion wouldn't have been fun for us, but since we were all on the same team, everyone simply contributed what we could. The finale of the level we were on was calling the army for rescue, and then holding off a massive number of zombies until a truck arrived to take us to safety. We made the call, and managed to hold back the flood of undead. The truck showed up, and everyone dashed for it. Two of us got in, and the other two got swarmed. Before we were able to jump back out to help them, the door slammed shut, and the truck drove off, leaving the other two to die, and the two of us in the truck screaming into our headsets. It was an excellent experience (well, not for the two who wound up zombie chow), and something that just wouldn't have happened in a non-co-op game.