Heh, that's cool!
I actually have a dodgy command-line utility which takes an SVG graphics file and turns it into a basic Mayhem Intergalactic map, so you can use
Inkscape as a map editor. You have to set production, starting priorities, etc. yourself though, and it messes up if you don't do what it expects. Some of the standard maps in MI were made using it. I can release it if anyone's interested - I haven't done so yet because it's really pretty dodgy.