Have we looked into what Wikia is doing? I bet they have something we can use.
http://help.wikia.com/wiki/Help:Notifications
These are bubbles which pop up for the user, but I see some things in their code which suggest you can get them by email. This seems to be all connected in their Oasis / Notifications module, but I could be wrong.
https://svn.wikia-code.com/wikia/trunk/skins/oasis/modules/
Inez wrote a bunch of this so maybe we can ask him.