Although it isnt CNC, its almost there.. I took delivery yesterday of a Tiger Stop "Tigerfence" system (that I ordered down at the Altlanta woodworking show) for my Griggio 10' sliding panel saw. Its a stepper and ball screw driven fence which offers a fast setting, and excellent repeatability.
To install, you basically remove the stock fence completely. Then drill mounting holes in the table skirt, and mount the Tigerstop fence, and adjust everything as to cut square and true again. Then set up the electronics.
Once the fence is set parallel to the blade, and square vertically to the table, you simply cut a piece of material and measure it. Then calibrate the unit - after which, any measurement you punch in drives the table to that setting quickly, and within a few thousandths repeatability. I used vernier calipers to check the measurements and this thing is BANG on!
Here are some photos, including the carriage in the retracted position... which is why it was pain to walk around it all the time to reset the stock fence.
I know some of you use the Shopbot to cut your sheet goods. For me, I still do all my square cuts on the slider.