Actually the xbox port of Zsnes (Never released, not done by Lantus) was a port of the SDL version which has (I believe might be wrong) a C/C++ processor core for easy portability.
He managed to get the port working in 1 evening
http://www.lantus-x....sp?TOPIC_ID=823Edit:: It looks like I am wrong the processor core appears to be asm but given the xbox happens to have an X86 processor in it should mean it's "reasonably" easy to port (He did it in a night so I guess it was easy to port).
People seem to spend longer bitching on these forums demanding a port than they will actualy playing it if the port is ever released.