The game shipped yesterday so it should be to retailers tomorrow. But, it's been ripped on the net already, so if you know where to look you can get it.
Anyway, this is a prequel to the console versions of Assassin's Creed. I just started playing it and sadly it didn't really impress me. The graphics are bland and the game holds your hand the entire way through. Framerate can get pretty choppy too. Though, I'm a big fan of the game (I even bid on that art book on Ebay), so I'm going to play it the whole way through.