Receiving notifications when user edits a node?
Newer versions of the Workbench Moderation module integrate with Rules.  I am not sure if the patch is in the stable tree, or whether you need to use the dev version, though.

Assuming you have a version that supports this, then 


add a new rule
for the reaction, choose Node: After moderation transtion
for the action, choose Send mail
if needed, you can add conditions based on the old and/or new moderation state.


After that, just configure the conditions and the email that gets sent out.