IoL4 (http://www.iol4.com/) is an L4-based microkernel that boots into Io (http://www.iolanguage.com/), which is another language that looks rather interesting. I've never got the Io VM to build on OpenBSD/amd64, which rules it out for me, though.

I'd like to do that with a Forth or a Lisp one of these days, time permitting.