I shot a little video of it with my cell phone.
The 4th axis is a Troyke 12 inch rotary table (very early model) with a servo motor and a RESOLVER for feedback.
Runs on my Series II Bridgeport Interact 2 mill that I retrofitted with EMC2.
Here's the vid:
[nomedia="http://www.youtube.com/watch?v=ag3XjCAXP14"]YouTube - 4th Axis milling on Linux EMC EMC2 CNC Bridgeport Interact mill[/nomedia]