- mc-pgp-decrypt-parser needs a lot of work. As-is, you get no data
       because the "Signature good" output (on stderr) from pgp ends
       up after the actual message, the opposite of what
       mc-pgp-decrypt-parser expects (This might also be a result of
       Windows or Emacs on Windows mixing stdout and stderr
       differently; <insert flame about start-process not having a way
       to handle stderr separately from stdout and depending on
       unreliable mixing semantics>). 
       This might be a place where ripping off from mc-pgp5.el
       would be productive. I'm still working on it. 

I hope this helps some.

        - Nathan