I know of 2 examples of Lisp being used to develop an OS (there may be more): one by Symbolics (called Genera) and the other by Lisp Machine Inc (aka LMI). Apparently both of these descended from code developed at MIT's AI Lab. Googling, it sounds like some of the source code for one of the versions was released as open source.
Of course, Lisp Machine Lisp (or Zeta Lisp, et al.) are not the same as Arc, but I expect that what you can do in one, you can do in the other. Small matter of programming :-)
The interesting question is not the implementation language, but what you intend to build.
