People are already starting to use Arduino due which is a Atmel SAM3X8E ARM Cortex-M3 CPU
There is also the 4pi and SmoothieBoard see [reprap.org]
Electrically all you need is a bunch of io lines (3 per stepper, endstops 3 or 6, hotend and heated bed via MOSFET, and any extras like lcd and sd card)
and some analog input lines for 2 thermistors and some serial lines for communications.
More problematic is firmware, your going to have to port something to your board or write your own... this is not trivial
There is also the 4pi and SmoothieBoard see [reprap.org]
Electrically all you need is a bunch of io lines (3 per stepper, endstops 3 or 6, hotend and heated bed via MOSFET, and any extras like lcd and sd card)
and some analog input lines for 2 thermistors and some serial lines for communications.
More problematic is firmware, your going to have to port something to your board or write your own... this is not trivial