In 2004 Peter Hochstein and Jeffrey Tenenbaum sued Microsoft over a 10-year-old patent for "communicating live while playing the same video game in separate locations." After six years of legal tomfoolery, a U.S. District Judge has dismissed the case.
Hochstein and Tenenbaum sued both Sony and Microsoft for patent infringement in 2004, claiming that both companies employed methods similar to the ones described in their patent to allow two players to communicate while playing a video game in two different places. Here's the exact wording, from the patent:
A local video game including a communicating controller. The controller receives local command signals created by a set of player controls. The controller also receives remote command signals received through a modem which were created by a remote video game through a similar set of player controls. The controller includes a synchronizer which produces synchronizing codes to be sent to the remote video game to synchronize the games. The synchronizer synchronizes the local and remote command signals such that both are received by a game microprocessor simultaneously. Memory stores the player parameters and are retrieved whenever the synchronization codas of the local and remote video games have not matched for a predetermined number of iterations.
It seems a bit of a long shot, but the similarities were enough to make Sony settle out of court for an undisclosed sum last year.