I find it fascinating that the actor model seems to be the model for creating reliable software. You can see it in Scala or Erlang at the user level, get it in MINIX3 at the kernel level. I think if you combined the two you could potentially create systems which stay up for years.
I have met a couple of QNX-based, also microkernel-based, systems that had uptime measured in years.
Lovely OS. I learned C on it.
MINIX reminds me of GNU/HURD. Since they are all Unix-ish from the application's point-of-view, I have hope they someday can more or less compete on equal footing with more traditional monolithic (it would be fair to call OSX "duolithic") OSs like Linux, BSD, Solaris.
Very usable desktops like the Gnome I am using to write this don't care much about what is under the libraries they link against. They would be fine on top of any OS as long as libraries provided the environment they expect. Oddly enough, the first time I ran Gnome was on top of IRIX.
