Well Erlang is running on RTEMS in production in industrial control systems http://www.grisp.org
Hard realtime processes to come
Of course. Apologies, I assumed that was a given. A large part of the appeal of Erlang the Language is Erlang the VM and the two aren't often divorced.
After all, as long as BEAM is running as a child process of a host os that is not hard realtime you can't guarantee much of anything.