Novelist John Beiswenger has filed a lawsuit against Ubisoft for similarities between his novel Link, published in 2003, and the overarching story of Assassin's Creed. Beisenger claims that his book details "the conception and creation of a link device and process whereby ancestral memories can be accessed, recalled, relived, and re-experienced by the user." Since the Assassin's Creed story is so similar, it therefore breaches his copyright, in particular, the concept of the Animus.
He also points out that his book and the game both reference the Garden of Eden, the forbidden fruit, and Adam and Eve. If that wasn't damning enough, the writer also pointed out that Link frequently mentions assassins and their battle for control of the device.
Beiswenger has filed for $1.05 million in damages and up to $5.25 million if a court rules that Ubisoft deliberately infringed his copyright. His final demand is one that will pain gamers the most: he wants to stop the release of Assassin's Creed III. In considering typical court procedure, it is very likely that this latter demand will be met at least during the process of the lawsuit in the form of a Temporary Injunction.
I haven't read this book, but based on the claims from the Original Petition, it doesn't look good for Ubisoft. If these allegations are true, then I will lose a great deal of respect for Ubisoft, and I doubt I will be alone. I strongly believe that there is a special circle of Hell for plagiarizers that is so terrifying, Dante couldn't bear mention it in his Inferno.