[Kiros72]

Well, when I was first going to take this on, I thought of a rather practical method.

Basically, whenever a post is edited, a reporting account would post in that thread notifying that X post has been updated.

That would mean that the thread would be seen as unread. Any subscriptions would see the reported message "This post <linky> has been updated for this reason," or something like that.

I think such a method would be fairly easy to implement - far easier than simply making the thread automatically unread. However, I know the harder method can be done because that would be similar to the attachment system (i.e. showing that the thread has an attachment somewhere in it from the forumdisplay script).