Out with the old (Games for Windows Live) and in with the new (Steam Workshop) as Red Faction: Guerrilla has been updated to remove the old online system. In its place is a full suite of Steamworks integration, including online multiplayer, trading cards, and more.
Steam Edition Feature Highlights:Misc Changes:

I gave the beta for this a test about a week ago and it worked quite well. If you own the game already, it should update to the Steamworks version automatically. If you don't yet own the game, you can pick it up for just $2.99 (USD) through Steam while it's on sale. That's a massive 85% off of its normal price!