Gaunathor: Well, it seems we have official word regarding the question of a non-Steam version. From a post of Frogboy on the forums:

"But there isn't going to a be a non-Steamworks version of GalCiv III because it would require too much time and effort on our part to do that. For starters, it would have to be a non-Multiplayer version of the game, requiring its own installer, requiring the removal of achievements, AI data mining, in-game mod support, etc. In short, it would be crippled."

The FAQ has been updated. It now has a few more questions, and some of the answers have been changed.

The one for multiplayer, for example, now states, that there will be online and hotseat multiplayer, plus some form of asynchronous play.

I guess, that is good news for people who care about MP.