This is a little odd, but, according to PS3Fanboy.com, a recent PlayStation Underground newsletter reveals a God of War musical track coming to the PS3 version of Guitar Hero III.
Kratos is cool and all, but he pre-dates rock and/or roll by thousands of years, so we're not sure specifically what the deal is, yo. The text on the ad reads simply: "Free GOW song for Guitar Hero III, June 5th." Time, as they say, will tell.
PS3Fanboy: Guitar Hero meets God of War on June 5th