There is now a Microchip PIC32 processor compatible Arduino board available.  A NorCal RepRap meetup member got one yesterday and it really works with the Ardunio software!  The board will accept Ardunio Mega 2560 shields.  It does offer huge possibilities with built in Ethernet and SD card hardware. We hope to have it running at the next meeting. Here are a couple of links for the board:

http://www.digilentinc.com/Products/Catalog.cfm?NavPath=2,892&Cat=18
http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=2095&param=en553910
http://www.chipkit.org/forum/index.php