Activision and Zynga in the world of video games, and TechCrunch reports that both companies have been sued by Walker Digital, a company founded by Jay Walker, best known for founding Priceline.com. Walker Digital alleges that both Zynga and Activision violate its patent, US patent no. 6,425,828, which concerns a "database driven online distributed tournament system." Specifically, Walker alleges that the companies violate the first claim of its patent which describes a "method of conducting a distributed electronic tournament for a plurality of players."
The suit names several of the companies' titles, including World of Warcraft, Call of Duty: Black Ops, Mafia Wars and many others (though not Farmville, surprisingly). We're not legal experts, but we'd argue that the word "tournament" implies a finite series of gaming events with a distinct winner, as opposed to the ongoing matches seen in the games cited by Walker Digital. Furthermore, the dependent claims in Walker Digital's patent make it pretty clear that it was intended to describe tournaments with entry fees and prizes, which certainly isn't the case with the games cited.
Walker Digital is seeking unspecified damages from Zynga and Activision Blizzard.