[blacksmith_tb]

I suppose it depends on if we're talking about server-focused OSes or desktops - for the desktop, there's Qubes[1] and I think it would be fair to say ChromeOS[2] should be mentioned...

1: https://www.qubes-os.org/ 2: https://en.wikipedia.org/wiki/Chrome_OS#Security

[oarsinsync]

Oh wow Qubes looks like a very interesting approach. I will be (somewhat hilariously) throwing that into a VM to try soon!