Man, the whole cube thing for workspaces in Compiz just blows the pants off Leopard's Spaces, IMHO. I'm sure Apple people just write it off as needless eyecandy, but I personally think it helps visualize where things are and it's easy to cycle through your workspaces. It's very intuitive -- I didn't find Spaces all that intuitive when I tried it on a friend's iMac. I suppose Apple couldn't use the cube rotation effect for Spaces, since they already use it to represent switching to a different user's account.