Back in March 2005, I mentioned on #lisp that I had some ideas for writing an X server in Common Lisp. Then I had to "put up or shut up", so I wrote an initial set of design notes (linked below). And then I couldn't leave well enough alone, so I started in on implementation (using SBCL-specific extensions).
As of late April 2008 work has resumed on CLXS, with a focus on cleaning up known issues in the codebase, improving the wire protocol handling, and providing at least stub implementations for all X protocol requests.
A darcs repository has been set up to hold the latest version of the code at http://www.lisphacker.com/projects/clxs/repos/clxs/
|CLXS design notes|
|Wire type system improvements|