Quite impressive! Worked without a hitch on the new iTunes 7.0.2 update.
One request - would it be possible for us to select exactly which graphical elements we want? For instance, I'd like to pick the Uno background, the "all aqua" buttons, but not the volume slider. I could see being able to pick and choose each element (play buttons, view buttons, browse headings, volume slider, bottom buttons, source highlight, scrollbar widgets) independently, and then choose which window style is wanted. The current preview would make it very easy to see what things would look like in the end, and since it's just replacing a lot of resources, it should just be a matter of a bunch of branch statements.
Of course, I've been known to drastically oversimplify coding jobs before. :)