Activision (NASDAQ: ATVI) can rock its shareholders just as hard as a blood-spitting Gene Simmons at a Kiss concert. And we all know why -- the Guitar Hero franchise is, simply put, one of the most popular videogames out there, and it is available for all the major console systems from Sony (NYSE: SNE), Microsoft (NYSE: MSFT) and Nintendo (OTC: NTDOY). It's also a pain in the neck for other publishers such as Electronic Arts (NASDAQ: ERTS), Take-Two (NASDAQ: TTWO) and THQ (NASDAQ: THQI), since they have to put up with the franchise's dominating power. But guess what, the inevitable has come to pass -- Activision is being accused of patent infringement!

Yes, you can't be very popular, you can't rake in millions and millions of dollars in profit for shareholders and expect to get away unscathed. Gibson Guitar, according to this Associated Press piece, believes Guitar Hero infringes on a patent it holds for a rock-concert simulator. The patent apparently goes back to 1999 and it contains a description for a system that uses a 3-D headset in conjunction with a musical playback. Activision decided to file a suit to get a court decision declaring that it is not infringing on any existing patent.