There is info about the SmoothStepper on this forum and also Gregs own forum.
http://www.machsupport.com/forum/index.php/board,65.0.html and
http://www.warp9td.com Basically the SmoothStepper does away with the need for a computer with a parallel port, it also basically has the pinouts of two parallel ports and also has additional inputs for encoders or MPGs. The normal way of setting up motors and all other I/O will be the same, ie you still use ports and pins and still use the Port column for defining which port they are on.
The SmoothStepper does the pulsing and as was said this does away for the need of a software pulse engine, leaving Mach to concentrate on the calculations. The pulse rate is at 4MHz max at the moment where the Parasllel Port is 100KHz, thats a 40 fold increase. Also even at 4MHz the pulse is super smooth
I have run the smooth stepper through the Pico motherboard that I am using on my milling machine that I am in the process of retrofitting. This Pico motherboard is tiny (100mm X 72mm), has a 1GHz embedded CPU and up to 1GHz of memory, onboard graphics, LAN, Serial, 4x USB and PS2 for mouse and keyboard. I tried running Machs Driver Test on this board and it wouldnt run, just locked the pico up, however with the smoothStepper it works perfectly, I have not had it running my new mill as its not ready, so I couldnt test at the speeds I will be running the new mill at. However I did have it hooked to my old mill and it ran it perfectly at the feedrate of the 3D programme which was 1000mm/min. see here
http://www.youtube.com/watch?v=bApuwkkXTb8 There is word of addon boards for the smoothStepper that will add to the I/O but not sure what or when.
Hood