Well, we are doing just that. It is the G2002 project.
It is an open source 6-axis, USB powered (remember, parallel ports and com ports are disappearing soon), 32-bit general purpose I/O all run by a Rabbit Semiconductor module. Right now it is running true 3-D vectors, constant contouring of anything you can draw in ACAD. Unlimited step pulse frequencies, (>4MHz) in 8 freq ranges of 65,536 evenly spaced velocities with 1,024 vectors per second on 6 simultaneous axies.
Open source means the schematics are open source, the firmware code (Z80 super-set) is open source as is the principle of operation.
It is open to everyone but CNC firmware developers are particularly welcome. The hardware is designed, it works perfectly but firmware is a work in progress.
Please visit the Yahoo Group "geckodrive" if you are interested. Go to
www.***********.com to get there if you aren't already a member.
See the "files" and "photos" section of the group to get oriented. Open the "G2002 Manifesto.txt" from the files section for a quick overview.
Mariss