As with all things in computer science, there haven been successful implementations of anything that we see as unsolvable in a Unix-derivative. It's sad that so little of even non-research results has been incorporated into mainstream operating systems. I'm sure nickpsecurity can expand on this in detail, but let's just say Burroughs, VMS, Eros, L4 are all things that come to minds as ancient production quality software which solved issues fundamentally. For a newer strain have a look at Barrelfish.
