Way back in 2008, we brought you the word that Konami was suing Harmonix, alledgeing that Rock Band infringes on Konami's music game patents. The case has been settled. The terms of the settlement have not been revealed, but all claims and counter-claims have been dropped, and both companies can now continue making video games (and money.)
Konami's original point was that it had two patents on simulated musical instruments, a music-game system and a musical-rhythm matching game, that they came up with in 2002 2003. Harmonix counter-suit claimed that the musical instruments in Konami's Rock Revolution infringed on their patents.
I'm no lawyer, but it does seem that Konami's big-in-Japan games Guitar Freaks and Drum Mania (and, for that matter, Dance Dance Revolution) use a lot of the same tech and ideas that found their way into Rock Band and Guitar Hero. Not that that means a patent was infringed upon, of course. Either way, the case is over. The dust has settled. Go about your day.