This isn't the first of these tribute albums I've seen with these artists. I had an Aerosmith one, and it featured members of Quiet Riot, Steelhart, LA Guns, and other bands from the 80s. I think there is a series of them.
I find it ironic that some of these guys (well, most) are from the hair metal/power metal era, and the 'grunge' era that STP first came about wiped these guys off the face of the earth.