First off I have to compliment you, great skin, can't wait to get the new beta and see it as it is meant to be shown. But I actually already have seen it, in my own good'ol build #448.
By Downloading the recenetly released Winamp 2 Plugin Manager and one of the already avaiable Winamp 2.x Transparency Plugin, I get what the below image shows.
If you want links to the Winamp 2 Plugin Manager, and the Winamp 2.x Transparency I will try to find them.
Or if you want me to take a screenshot with a nice right click so you can see this build #448, I can do that too, anything. Just let me know, I just wanted to write this quick, to get this info out.
[in an effort to avoid what I mentioned above, here you go]
(note, niether of the above files are made by me, and the only reason why the second one does nto direct you to the author is becuase there are quite a few of this type of plugin available, and I could not find the exact one I first got.) (Which by the way actually has problems with some windows in winamp3, which I don;t know is a result of the wa2 mgr plugin, or the transparent plugin)