The rabbit code is written in 'Dynamic C' which is based on ANSI C.

The application code hopefully would be portable (although it is not written by me!), the main differences would be the OS (Dynamic C uses uCos II I believe) and of course the drivers for the CAN, TCP/IP and 1-Wire would need to be modified.

One other thing to mention is that there will be new applications coming along in the near future so the DS80C400 may be used as an alternative to using the rabbit.