Steam – No multiplayer on total war

Playing Civ V in offline mode should allow you to play other steam games simultaneously. I feel compelled to point out, however, that steam only allows one copy of itself to run at any given time, so short of some technical tinkering, you're still limited to one game / steam / computer.

I don't think that there is a physical copy of civ V. Everything I've read indicates that its going to be exclusively digitally distributed.

As far as I know, Steamworks is going to function as the game's DRM which means that even if there's a physical install disc, you'll need steam to play it, even in offline mode.

As several people have mentioned, it is now possible to be logged in on multiple computers at once. Only one computer can be playing a game at a time though. If you start a game while another computer is already in one, you will be notified and told that it will close the other game if you start.