The link between the games is pretty tenuous at this point, actually. Players of both the Xbox and Facebook games can choose to represent either the Allied or Central powers in World War I, and their performance in either game contributes money and control of territory to their side in an hours-long real-time war. Players will soon be able to link their Xbox Live accounts to the Facebook version of the game, receiving a point-multiplying bonus for doing so.
It's an interesting concept, but one I'd like to see taken a bit further. Why not link Xbox Live board games like Uno Rush or Carcassone to compatible Facebook versions, so people can join in from their computers or their TVs. Or have your Xbox Live achievements automatically post to your Facebook wall. The possibilities are endless, and just beginning to be explored this week.