The publisher has launched a suit against Optical Experts Manufacturing, which is based in North-Carolina. They contracted them to reproduce PC copies of Assassin's Creed.
They allege that one of their employees took a copy home and leaked it over the net six weeks before the games official release - costing millions in piracy.
The pre-release version was downloaded over 700,000 times they say, with only 40,000 copies selling at retail in the US through June according to NPD. In addition they're also claiming a hit to Ubi's reputation from the subsequent negative comments on the pirated version of the game.
The pre-release version was apparently given a bug that would crash the game partway through and then removed in the full retail version. This was designed to prevent the spread of the game illegally but it seems only lead to confusion for gamers as reviews of the pirated and official retail clashed, which they claim caused "irreparable harm" to Ubisoft.
Copyright infringement, breach of contract and negligence - which Ubi wants OEM to cough up no less than $10 million for each in its lawsuit for "an extraordinary breach of trust and gross negligence" from the manufacturer.