I am not pretending to know too much about what I am talking about here…
But from what I understand, RS485 is capable of long distance communication. Ever think of creating a shield with this in mind, so one can communicate over a tether from 500’ to 1000’?
It would be nice to have something similar to this long distance communication that would be “FEZ” for my Underwater ROV project.
Mike in MN
Just use RS232 then add an RS485 converter 
Search google for “RS232 to RS485 converter”
See this for an example but there are thousands of converters on the web
http://www.rs232-converters.com/rs232_to_rs485_converters.htm
By the way, your name has CNC in it…have you ever made CNC machine yourself or you have experience with G-code?
Well thank you for the prompt response.
That being said for the RS232 to RS485 converter, would the FEZ work in the same manner with a USB to RS485 converter.
I guess what I am asking is, would a person have the same control over FEZ.
Mike in MN
RS485 is different in a few ways, it uses differential transmission lines and you can have multiple addressed devices on the same line. Take a look at: RS-485 - Wikipedia.
From a programming point of view it just looks/acts like any other serial device. You have to know the protocol the remote device expected to speak.
Chimp, FWIW, I do CNC stuff: www.soigeneris.com. Part of my interest in FEZ in as a development platform for a few CNC related ideas I have.
I daydream about a CNC machine controlled by FEZ…I would help you in anyway I can 
Jeff,
I know I have tons more reading to do, thanks for the direction. There is just so much involved in all of this, but it’s truly fascinating…
FYI…Cool! on the soigeneris site. I can program a CNC all day long, but trying to wrap my mind around all the logic and communications with them HURTS!..
Mike in MN
I thought about using output compare to generate a series of pulses to control a stepper motor. Ideally though it would be able to write to a whole port (8-bits) at once. You could have a buffer of precalculated movements for multiple steppers that all get clocked out at once. A port wide write would let you control 4 steppers at once.
You can do port write with register access but this requires some knowledge of the processor registers. You can also use a shift register on SPI bus