Announced in May, Valve's Steam Cloud service will be up-and-running in time for the arrival of the Left 4 Dead demo – at least for those who've pre-ordered the game – on Thursday, Nov. 6. Steam Cloud will store player's settings for individual games server-side, so that they can start playing with their preferences (keyboard, mouse, etc.) intact from any PC with the Steam client installed.
Left 4 Dead will be the first game to ship with Steam Cloud support built-in; Valve plans to patch older titles to play nice with the service, and is sharing its code with Steam publisher and developer partners at no cost. The service is similar in some ways to Apple's MobileMe "cloud" based email, contacts, and calendar syncing ... hopefully, Valve's creation will actually work as advertised.