Assassin's Creed Brotherhood was released for Xbox 360 and PlayStation 3 back in November 2010. The PC edition was initially expected to launch alongside the console versions, until Ubisoft revealed otherwise in September. Hopefully it'll be one of the PC games Ubisoft tones its DRM down for.
Ubisoft confirmed yesterday that a mysterious, new, "packaged" Assassin's Creed game will be released some time this year. Not a Facebook game then, at least.