Good guide! When I had the netbook launcher installed (to try it out), I followed your guide for a much prettier experience.
I forget the name of the exact file, but in the same folder as the window.svg file you modify below is another file that is the background behind the icons (the middle section of the screen.) It is a PNG file, and the opacity of that one can be changed in gimp. (I no longer have the netbook launcher installed, or I would give more specifics). (3 Notes: 1) gimp is not installed on the netbook version by default; 2) you need to edit the PNG file as root; 3) in gimp you'll have to do a "Save as" PNG to get around some warning message about the plug-in. But it does work!)
Enjoy, and thanks for the guide!