i donno if you guys know this (its sorta simple but way sick so i thought i'd post it), but if you go to system prefrences then screen saver, there's an option for the album artwork screen saver. if you want that as a permanant background (it wont switch albums but its still dope) do this.
hold the cmd + shift buttons, then click "test"
the screen saver will now show up, and then click the number "3" on your keyboard
this takes a screen shot of all your album art, and you can make the screen shot your background. it looks pretty sick.
here's a picture