iTunes hasn't been brushed metal in almost 2 years. It's using a flat medium grey (the same overall tonal shade of the metal texture but with no textural qualities).

I actually prefer some variation in the OS and don't like everything looking the same. I don't necessarily want the Finder to look just like iTunes because it's NOT iTunes. In fact, I even prefer the coloring of the original Unified look used in Mail that shipped with Tiger. Mail too will go darker in Leopard.

As mentioned, Uno, a third party application allowing some theming defaults to be changed, should allow this to be altered for Cocoa apps.