It surprised me how little effort developers put into stopping griefers. I remember in BF1942 getting more annoyed at Dice than the teamkillers themselves, because dealing with them would be so easy. Killed a team-mate? Your next respawn is delayed one deployment cycle. Killed two team-mates? That's two cycles, or a minute IIRC. That gives legitimate players an incentive to be a bit more careful and gives griefing players a whole bucket full of frustration - a taste of their own medicine.
I don't know how this would fit into Day Z as Arma2:CO hasn't been on sale yet. PvP shouldn't be out-right penalised as the risk is part of the game as I understand it. So killing a player shouldn't be a death sentence for yourself, like a wanted flag would be. But how else to do it? Hmm.
Day Z's biggest influence could well be the number of sales Arma 2 has racked up. I'm sure developers and publishers are looking at this and not only seeing the potential in the game play, but in the flexibility that Arma offers that results in people doing their work for them. Everyone's a winner.
I would give Day Z a lot more time than other games. It's an alpha version, and it was an experiment to begin with. It's not right for us to congratulate him on his experiment and then jump down his throat when a balance experiment goes wrong.