This patch to org-mac-message.el should make it show growl notifications
when searching for flagged messages and growl is running, and work
silently otherwise.

It's a little more complicated than it needs to be, since as noted in a
comment about the "double-tell" idiom, using the creator code to find
the application is probably not going to work unless the application's
name is exactly "GrowlHelperApp" anyway, but I am not motivated to
simpilify this more now that I have it working.  Someone else is welcome
to improve on it.

Anyone is welcome to use this patch for any purpose.  I hereby place it
in the public domain.