This script came in real handy earlier when I was using GIMP. One button click brought up all of the program windows. I did have a problem though in that sometimes when GIMP would spawn a window (for instance for the Drop Shadow plugin) it was somewhere behind other windows. Clicking the launcher brought it up of course, although not to the front. I doubt it's your fault. Probably something with focus stealing prevention in Metacity (which is what causes anything opened in Thunar to appear in the background).
The Expose feature in Compiz makes the integration work better. You never really REQUIRE a task list. By the same token it WOULD be nice to have another version of the window list applet that only showed program icons instead of the full program name (and could be grouped as well of course). That combined with this would basically give you the "full" doc experience without having to use any external things like kiba or cairo or avant, and would continue to work even if you switch off your composite manager .
On another note I do wish there was a way to bring a specific window from an application to the front though easily. I doubt this is possible without some kind of Gnome/GTK integration.