According to a report on Engadget:
"We're not exactly clear on how Gibson's legal team managed to license all those brand names and guitar designs to Activision for this many Guitar Hero games before realizing that the company maybe-sorta had a patent on the idea, but here we are: Activision filed a lawsuit yesterday asking the US District Court for Central California to invalidate a 1999 Gibson patent on "simulating a musical performance," because apparently Gibson's bugging them about it since January.
Wait, just January? Seriously, people, you'd have thought this would've come up by now. Anyway, Activision says that Gibson is still a "good partner," just that it "disagrees with the applicability of their patent and would like a legal determination on this." We're sure it would. Gibson's patent apparently involves playing an instrument of some kind along with a pre-recorded concert while wearing what is described as a "3-D headset," so there seems to be some overlap, but we'll see what the court says -- something tells us explaining Guitar Hero to the judge is going to be relatively amusing.
Update: On reading the patent, Gibson's system is designed to be used with a "musical instrument" -- and no matter what the Guitar Zeros have to say, we don't think Guitar Hero controllers really qualify. It'll definitely be interesting to see what the court has to say about that, no? So stay tuned.. the courts may decide whether a controller is a musical instrument.