Does this exist? "Reason for Edit"

Sorry I couldn't find an example offhand, but I thought that it would be neat if someone could figure this out, or if it already existed.
The mod would make it so that when a moderator has to edit a post (language, offensive, etc) they would have the option to put a "reason" into the edited post. So underneath the post just above the signature it would say
"Edited by ZacFields at 01/04/06 at 22:21 Reason: Post was cleaned of offensive statements."
Does anyone know of this existing at all? If so, can anyone get it working on IM?
Zac
The mod would make it so that when a moderator has to edit a post (language, offensive, etc) they would have the option to put a "reason" into the edited post. So underneath the post just above the signature it would say
"Edited by ZacFields at 01/04/06 at 22:21 Reason: Post was cleaned of offensive statements."
Does anyone know of this existing at all? If so, can anyone get it working on IM?
Zac