Oh man, you're right, I didn't remember the game came out tomorrow! I was going today anyway, I hope it's not too late, as they sometimes get the games in advance. I almost couldn't preorder Batman:AA a few months ago because they got the games a week in advance (the awesome $40 deal). But in the end it worked because they had ordered an extra copy.
I'm guessing they'll have a whole lot of GoW3, it would be stupid to only get enough for the pre-orders, it's like one of the most anticipated games of 2010.