Been thinking about this one for a while, and finally started working on it today. So far I've got it able to store the edits as they're made (which is by far the easiest bit of the code) and added an item to the menu to view the edits.
It's also, interestingly, exposing a weakness in the post display, in that there's no way to alter the items (other than those in the menu) by way of a hook - nor is it possible to do what Niko's mod did and have the 'last edited' text be a suitable link. Not yet sure how I want to deal with that.
As far as the menu goes, the real struggle - such as it was a 'struggle', depending on your definition - was making the text be different between menu instances, to include the number.
But here's what I have so far. It's not very exciting, because I haven't gotten onto the real meat of the display yet, but that's OK, I haven't spent that long on it yet.