(As far as I know,) you can give a section of your county to a friend with permission and you can play at the exact same time. So while you are playing, if your friend starts a coal plant then you could suddenly notice more power in your city. Basically, co-op in which you can't really step on top of each other much.
Once again, they significantly improved their game from the last one.
New features in this game include multiplayer, greater city specializations, greater detail (down to the last sim)
check it out at [link]
So, are you going to play it?
Have you ever played a previous sim city? How did you like it?