FunOS: Mostly functional (programming) OS in design, and fun to do system programming in; all policy code in kernel to be in Scheme. To support multiple APIs, and be runtime extensible: replace parts of system on the fly and, within security constraints, by ordinary users.
Lisp-based OSes: History, considerations for operation, list of projects with links (some updated, some not).
LispOS Info Page: Brief history, and link to mail list archive, begun April 1997, closed February 1999, by Richard Coleman (of ZSH), to coordinate efforts to make a free OS to return to users the power of Lisp Machines.
NASOS: Not Another Scheme Operating System: Ideas, wish list on how to build Scheme OS to run on cheap PC hardware, and some platforms that may succeed it. Intended to be mildly radical yet doable.
Thoughts-on-a-LispOS: Brief description, with careful wish list outline; wiki.