software packages, configuration files, boot scripts and the like are all managaed in a purely functional way, that is, they are all built by deterministic functions and they never change after they have been built.", from http://nix.cs.uu.nl/nixos/index.html
One thing microsoft has being doing which is interesting is singularity.
its just not clear what these projects are trying to fix. i am all for good research, indeed a lot of it manifests itself in linux, bsd etc...but chucking a decade+ of debugging, userland tools, docs, etc...its a nonstarter. who is downloading minix3? purity of design at the os level has few takers in the real world. people want high performance, small footprint, and security. linux is delivering on these as good as anything else actually in use by mass markets. there have been other softball comments here, like the offhand comment that linux is not reliable and secure, but i haven't seen any substantial commentary on why this is the case. try these comments out on the kernel mailing list if you want to be brave AND ontopic. i say all of this as a freebsd user, so don't construe my defense of linux as a political bias.