Real guitar maker, Gibson Guitar Corporation, is accusing the simulated guitars used in popular video games like the "Guitar Hero" series and "Rock Band" of patent infringement.On March 21, 2008, Gibson filed two lawsuits for patent infringement in Nashville. One of those lawsuits names Harmonix Music Systems, MTV Networks and Electronic Arts as defendants. Apparently, these are the companies that market and distribute the Rock Band game and at least some of the Guitar Hero titles. The other suit was filed against a number of major retailers like Amazon and Target who sell those video games.Gibson's patent, U.S. Patent No. 5,990,405, is titled "System and method for generating and controlling a simulated musical concert experience." The abstract to Gibson's patent - which often, but not always, explains the gist of the invention - states as follows:"A musician can simulate participation in a concert by playing a musical instrument and wearing a head-mounted 3D display that includes stereo speakers. Audio and video portions of a musical concert are pre-recorded, along with a separate sound track corresponding to the musical instrument played by the musician. Playback of the instrument sound track is controlled by signals generated in the musical instrument and transmitted to a system interface box connected to the audio-video play back device, an audio mixer, and the head-mounted display. An external bypass switch allows the musician to suppress the instrument sound track so that the sounds created by actual playing of the musical instrument are heard along with the pre-recorded audio and video portions."There are, however, some differences between the system described in Gibson's patent and Guitar Hero. For instance, Gibson's patent - which was filed back in 1998 - describes an invention where "the video and sound portions of a musical performance or concert is pre-recorded on a video tape, digital disc, or other media containing audio and video tracks." A video game run on by a microprocessor is obviously different from a video tape. Indeed, Gibson's patent says that "[o]ne advantage of the system is that no computer is needed to operate or control it." Another distinction may be the use of real-life "musical instruments" as opposed to a plastic, guitar-shaped video game controller. In fact, Gibson's patent goes so far as to refer to the user as a "musician." Now I've played Guitar Hero a few times, but I don't think I'd call myself a "musician." My virtual rock star skills have yet to translate into actual guitar-playing ability.Of course, it's too early to tell whether any of these differences will mean "game over" for Gibson's infringement case. But it's a safe bet that the defendants are already preparing their defenses.