I created this SVG picture some time ago. It is a simple 16:10 wide-screen adjustment of the standard "Etch" wallpaper. I have kept the swirl in the middle small and only resized the background. That way the curves are having the same 4:3 proportions while the swirl will not become too big.
However I lately discovered that there is already a bug report about that on http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=473481.
Thanks to Jorge Barreiro Gonzalez I have now fixed an issue with transparency as well. The only difference between his version and mine are the curves in the background.
Thanks to André Luiz Rodrigues Ferreira for the original!