Harmonix today mentioned that the new Wii version of the Rock Band guitar won’t be compatible with the Guitar Hero III guitar and vice versa. Sadly the same story is true for the PlayStation 3 (and presumably PlayStation 2) versions of both games. The Guitar Hero 2 & 3 owners on the Xbox 360 are in more luck as Joystiq’s “guitar compatibility guide” shows…

Click to enlarge the overview.
Thats stupid u cant compare since RB came out later and it has the solo keys its not RB fault GH is out of date -_-