In an interview on gametrailers today about the 360 version of Unreal Tournament 3 with Mark Rein, the interviewer asked him what he thought about piracy issues on PC.
He said he was going to do whatever he could to fight it, and mentioned that the PC Gaming Alliance is trying to do just that. He also brought up Steam, pointing out that Valve has done a great job with it, and although it won't end piracy, it's helping. He said Epic's games have been very successful on Steam, and since they have only been on Steam for a little over a month, I'd say this is very encouraging.
As a side note, Call of Duty 4 is still the #2 selling game on Steam today. It's only behind Team Fortress 2 which just dropped $10 in price to $20. I'd say Steam is definitely not only successful for Valve.













