In a conference call with investors, Activision, who received Guitar Hero as part of their acquisition of Red Octane, threw the first grenade against Harmonix's upcoming Rock Band saying that it "wasn't surprising that [Guitar Hero] has attracted imitators." Activision is essentially saying that Harmonix was imitating Guitar Hero by creating Rock Band. The humor here being that Harmonix actually created Guitar Hero for publisher Red Octane before the Activision buyout. If Activision wants to get technical, their Guitar Hero is an imitator of Konami's Guitar Freaks ... but that's getting nitpicky.
We can only imagine the Activision execs didn't take their modern gaming history, because without Harmonix they wouldn't be bathing in their Guitar Hero money in the first place. In the call to the investors the Activision execs say they do have a competitive advantage against Rock Band due to Guitar Hero's significant brand recognition. They also said they've done well in the downloadable sales department with 200,000 takers of the Guitar Hero II song packs on the Xbox 360's marketplace. And those song packs were from the original Guitar Hero, which was done by what company again? Oh, that's right -- Harmonix.