There are two types of edit. One is a change to the text because the poster made a typo, or posted the wrong info. The other edit is an addition to a post, and this is something I do. Your post may be the last in a thread, and you may want to add additional information without creating a series of posts by a single member. It would be interesting to be able to find these posts. Maybe we could tag them to make them easier to list. Tags such as [UPDATE] or [ADDITION] could be used.
I won't even try to automate detecting the difference, but it happens a lot indeed. People adding a comma or fixing a typo. Those can easily be spotted by comparing the old and new backup, and those cases are not the reason I created this topic.
Another advantage of this is that such threads would not be bumped, but an alert would allow interested readers to find them.
If the last post in a topic gets edited after I've read it, it shows as

on the
board overview. But it doesn't show as

on the
Watchlist. That could be a good feature to add to the forum.