For UNIX, try using the system's rsh command (remote shell), or ssh (secure shell). Or you could use Net::Telnet to login to a remote machine and execute the script that way. If that's too insecure, look at the SSH modules.

PVM and Parallel::Pvm might be worth a try as well if you want to get into distributed processing.

JJ

Update:
Or XML-RPC. Or SOAP. There are quite a few ways to run remote programs...