<a href="http://www.eecs.harvard.edu/vino/vino/">VINO</a> (at Harvard)
is an *(OS) built of reusable, replacable components
that can be organized by the end-_(user), even code running in
kernel mode. Their motto is that the kernel should provide
mechanisms, not policies, and let the end-_(user) decide of what
policies to apply. A concept springing up in most new _(OS)
projects and that we can only agree with.