I’m at the Metalab in Vienna and the guys here are working with a CNC Router to cut out Invaders! They’re using CamBam, which is an open source program for Windows. – Link
Update: after seeing it work, I’m impressed with the fact that this software takes into account the size of your tool, the only downside is that it’s kinda clunky. If you get it to work, take lots of screenshots to use as notes!