Call of Duty 4 Modern Warfare Easter Egg - Developer's Logo

On the multiplayer level Backlot, go to the building under construction. It's the only building with a basement, has a staircase, a mounted machine gun, and two or three ladders. On the ground floor, face the staircase. Go out the door to your left. Look along the first wall you see outside through the door. On the wall is Infinity Ward's logo painted on like graffitti.