This is a rather amusing article about seperating gaming from reality. My favorite quote (the game in particular this dude is talking about happens to be Quake 3) is:
"I'd play it, then walk out into the office corridor and realize I was looking at my co-workers as potential targets," said Taylor. "I was so used to killing anything that moved."
I identify with that on so many levels, although while at work it doesn't actually require me to have played hours of Quake beforehand to feel like that.