If my Ghost Recon* sessions are any clue, one of the hardest things about urban warfare is peeking around corners. Especially if you're going to take a shot. Your eyes are attached to your head, so you have to stick out your most critical body part for quite some time, long enough for anyone to take notice and to remove bits of it.
Welcome the cornershot, a combination rifle/pistol with a camera and monitor. At this rate I would imagine it would only be good for short distances, and the defense industry waits for cameras and displays to get better.
*special forces-based FPS