i am almost positive that the art comes from AMG, not gracenote. maybe gracenote contracts with AMG for art, or maybe Gracenote doesn't do art, or maybe winamp doesn't use gracenote art if gracenote does do art.
but many times i have seen that the AMG art is an exact match, like not just the cover, but the scan of the cover, like if it was over exposed or an alternate or whatever.
winamp sux at getting art. its a big weakness, and forget it for comps. WMP does art much better, and i think also uses AMG.