language environment depending on file

[slanning]

I'd like to have emacs change the current language
environment depending on what file I'm editing.
For example, all files ending in .mc, I want to
edit in UTF-8, whereas otherwise use my default
language environment.
  I tried this

  (add-hook 'mmm-mode-hook
    '(lambda ()
       (make-variable-buffer-local 'current-language-environment)
       (set-language-environment "UTF-8")))

in ~/.emacs, to try to set the language environment
only locally to a buffer that's loaded when mmm-mode
is started (so really, it's more than *.mc).
The problem is, it ends up changing the language
environment globally, so after I edit a .mc file,
any other file I edit is edited in UTF-8. So I'd like
a per-mode way of setting the language environment
or something. I guess I could add a similar hook as
above for every other mode, setting language environment
back to what I want for the default, but that seems
pretty ugly.