When Call of Duty: Modern Warfare 3 launches on PC on November 8, it will make use of Valve's Steamworks service. This means it will support offline play, auto updating, achievements and "more" according to Valve -- this may well include facilities such as cloud saving, allowing players to start a game on one computer and continue it elsewhere later. Steamworks will be used on both digital and retail PC copies of the game, also providing the handy side effect of incorporating an unobtrusive DRM solution which most PC gamers don't object to.
Valve also notes that Modern Warfare 3 will support dedicated servers for multiplayer from day 1. Activision hasn't yet confirmed how it's going to police this alongside its Call of Duty Elite service, as the company has previously indicated it wanted to ensure the prizes on offer for official tournaments wouldn't be gamed by server manipulation. Modern Warfare 2 notoriously removed dedicated server support when it became clear that cheaters and hackers were spoiling the experience for less "hardcore" players, and Black Ops offered dedicated server support on PC, but only when rented through an exclusive provider. Given Activision's desire to keep a tight ship with regards to stats on Elite, it's entirely possible that they'll take this exclusivity approach once again -- though the official word is yet to be confirmed.
PC owners can preorder Modern Warfare 3 from Steam right now.