Let's throw out the "let's check if he's an idiot" tests and get to the beans:
One computer. Another computer, possibly over ethernet, showing up as a "CPU" for all OS/program purposes on the first.
Is this possible in Linux? Where should I start looking? Are their projects dealing with this? I vaguely remember someone writing an ARM core emulator that utilized a rarely used feature in linux called an "external processor" which let his little microcontroller run threads.