As of the latest WoW patch (release date August 22nd, 2006) you can now control iTunes from within WoW without having to switch between full screen mode and windowed mode. This wasn’t a huge issue for me as I usually play WoW on my G5 System using a Microsft Wireless Natural MultiMedia Keyboard which allows full control of iTunes but it’s going to be a huge help when playing on my 15” MacBook Pro.

You can setup the controls through the WoW Key Bindings configuration window.

WoW iTunes Control