I would LOVE to build a modern-day operating system using a high-level programming language, even if it were just a pedagogical toy. I love Unix, but it’s not (and shouldn’t be) the final word on OS design.

In the meanwhile, Project Oberon from the late Niklaus Wirth (http://www.projectoberon.net/) is a good example of a pedagogical operating system (and programming language) that isn’t Unix. Project Oberon was heavily influenced by the Cedar and Mesa projects at Xerox PARC.