Harmonix has confirmed for GameSpot that it has signed an exclusive deal with Fender Musical Instruments to feature their guitars exclusively in Rock Band, and to base the upcoming guitar peripheral for the game upon the company's most famous model, the Stratocaster.
Harmonix also said the game will feature the Roland Corporation and BOSS brands, known for their synthesizers and guitar effects pedals respectively. However, Rigopulos would not say whether those companies would have their names grace Rock Band peripherals, or if the licensing deals were exclusive.
One last bit of information was stated by Harmonix president and co-founder Alex Rigopulos "The team at Harmonix feels that interoperability between various music games and peripherals is in the best interest of the gamers, so yes, we do intend to support the existing Guitar Hero guitar controllers, as well as other third-party guitar controllers, to the greatest degree possible in Rock Band, having said that, there will be some cool new features of the official Rock Band Fender Stratocaster Controller that aren't present in the existing Guitar Hero controllers."