<A HREF="http://plan9.bell-labs.com/plan9dist/"
  >Plan9</A> *(OS), or what _(Unix) should have been
(originally by _(Bell Labs) from where _(Unix) came).
It's a commercial _(OS), but freely available for academic use.
See its <A HREF="http://www.ecf.toronto.edu/plan9/plan9faq.html"
  >FAQ</A>.
It got everything right as for proposing a _(uniform) system interface
(the _(dynamic), per-_(process) name->channel "_(file system)" thing)
but is still wrong by using a _(low-level) _(programming language)
with coarse-_(grain)ed system _(abstraction)s.
(another page <A HREF="http://www.well.com/~aleks/CompOsPlan9/index.html"
  >here</A>)

See its successor, _(Inferno).
