The people in my hallway at work are like zombies. I smile at them as we pass eachother enroute to our respective offices, but they stare blankly back at me as if to say, "Who are you to presume to interact with me? You are nothing but a bug on the wall."
Granted, they are not in my group. We will never be required to work together to in any capacity. But should that preclude any attempt at friendliness?