Wow - lots of interest here. As Hood said "Good for Mach" - and us too!!
A good solution should work through Mach so that current position is always known - or "closed loop to Mach" . I think that's the goal everybody is talking about.
Should work well on anything - plasma, laser, waterjet, etc.
Once the basics are worked out, I'm expecting that several entries will pop up for consumer sales. The trick will be making one that is low priced for the masses.