"City Specializations" will allow cities to be tuned to specific industries, as in this industrial town. You'll need to be wary of the side-effects -- pollution is obviously a problem here, and that could affect your friends' neighboring cities in multiplayer. This is the city I'd build if I were playing with Al Gore.
Another interesting note: the smog exiting the factory towers actually represents pollution entering the atmosphere.
“There are no visuals in the game that aren't bound to meaning,” said Quigley. “There's nothing in there that's there just for the sake of filling up space and making activity. Wherever there's activity, whenever you see a smoke puff, or a gear turn, or doors open or close, it's because the simulator is making that happen.”