On  5 Oct 2011, jasondunsmore@gmail.com wrote:

> Julien Danjou <julien@danjou.info> writes:
>
>> On Wed, Oct 05 2011, Jason Dunsmore wrote:
>>
>>> Is there anything else I'm missing?
>>
>> Are you using Emacs 24?
>
> I'm running Emacs 23.2.1.  Does it require Emacs 24?

As Julien said: It does require Emacs 24.

But you can bind `org-contacts-message-complete-function' directly to a
key (You need to wrap it though) and bypass
`completion-at-point-functions':

#+begin_src emacs-lisp

(add-to-hook 'message-mode-hook
             (lambda () (local-set-key (kbd "TAB")
                                       (lambda ()
                                         (interactive)
                                         (org-contacts-message-complete-function)))))

#+end_src

Michael