Microsoft research is working on Singularity which, if I gather correctly, is an OS written in C#. They say it’s about reliability more than performance. It has to be if it’s going to use .Net’s CLR. That thing is bloated!
Singularity wouldn’t be a very good name for an OS. Especially for Microsoft who already has a bad image as a monopolistic giant trying to extend its monopoly from desktops to the internet. (I’m talking about the theoretical physics meaning of singularity. That’s a place where space/time come to an end.)