Yeah, all our friends don't allow their kids to play shooter games. But because of older brother's my sons got exposed. So then my wife and I started playing Call of Duty 2 and not my boys have lost a little interest. It's not as cool since the parents started playing! One day, one of my sons friends calls up and asks if he was online. He replied, "No, that's my parents playing." Too funny! Now in my household my wife is the curse-word police. So we started playing Call of Duty and when the zombies start attacking she gets all excited and starts cursing like a sailor. My sons are snicker and I am laughing because it's just too funny. So now when my wife plays, my son says "Mom uses a bleep gun". Because she bleeps all the time.
I am mixed about the shooter games. Many, many times we have had the conversation games are make believe and you should never ever hurt anyone. It is a tough conversation. My son's also play Minecraft which is a little violent but teaches kids how to program and create 3D worlds in first person 3D interface. So my sons are really good at creating Minecraft worlds. It's a tough conversation about what is appropriate and what is just harmless fun.