Looks like they have their hands on the code and are making changes, but haven't put the actual code on GH yet (maybe still working on getting permission?): https://github.com/Interlisp/medley/issues/2#issuecomment-66...
What we have is access to the source code for the D-machine emulator that Interlisp-D/Medley Common Lisp ran on in the 1980's.
The emulator was quite usable on 1980-s hardware - I worked for the company that sold it in the late 80s and early 90s.
We are still deciding stuff like what exact open source license to use, and how much priority to give to the two main goals:
* Historical - can it run old system dumps with important systems like NoteCards, LOOPS, LFG...
* Modernization - integration with host OS (clipboard, file system, networking), increasing memory space, adding Unicode