Singularity - A C# Operating System
Check out the Channel9 Video on the Singularity operating System. From the C9 page: Singularity is a research project focused on the construction of dependable systems through innovation in the areas of systems, languages, and tools. We are building a research operating system prototype (called Singularity), extending programming languages, and developing new techniques and tools for specifying and verifying program behavior. Oh, and the operating system is built in C#.