Not that I know of, but you could easily make one; just create an event module to fire on c_post or a_post, then call :
qa_send_notification($userid, '@', $handle, $subject, $body, $subs);
The badge plugin is a good example to show how this could be done, since it has both an event module and a notification function (the latter in qa-plugin.php).
More on event modules here:
http://www.question2answer.org/modules.php#event