This theme is a dark grey colourscheme for the Clearlooks engine. It is pretty generic and can be edited easily. At the bottom of the gtkrc file is a commented section for setting GAIM's buddy list background (just give it a valid filename).
NOTE: This theme is designed to work with the original (and best) Clearlooks engine, in other words if your system has the shiny "Clearlooks 2" installed then this theme will look awful. This is not my fault, it is the fault of whoever merged 2 different themes under the same name rather than keeping them seperate. For reference Ubuntu Dapper uses Clearlooks 1, but Ubuntu Edgy uses Clearlooks 2. To get Clearlooks 1 on Edgy I downloaded the source for Dapper's gtk2-engines from packages.ubuntu.com, compiled it into a package with checkinstall then fiddled with the control file to stop it getting overwritten by updates. Please comment if you would like me to explain this on the Ubuntu help wiki and put a link here. I only use Ubuntu, so haven't messed around with any other distros' systems.