Originally Posted by GRUNTERSDAD
p.s. I just checked iTunes and there are 160 AC/CD songs there by various artists, so at least in time they are selling the rights to their music.
The way I understand it, ANYONE can re-record and release a song without the original artist's permission (as I heard from a Paul Anka interview about his 2005 album of cover tunes). If you want to use the ORIGINAL version, you need permission (as is the case with Guitar Hero/RockBand tracks or any movie soundtracks).
So that's why you will see their songs by other artists on iTunes.