Looks like there is a Multiplayer project developing for SF. The good news is that the tool its being developed by the lead programmer of the game know as "Leva Opaki" in SF forums, the bad news is that is not official and is developed by him in his free time, wich means also that they have not in mind to release an expansion or a new game with MP included.
You can start a server with console commands...its still in testing and development.
More info:
