I've got most of the ForumNG discussion page working, but there's quite a lot left to do too - the fancy AJAX stuff is half-done, and I haven't done any of the controls that go along the bottom of the discussion yet (lock, move, join, view readers, export). Also, I haven't applied the pretty blue OU theme to it. So a screenshot of that can wait for next week.
Instead, here's the History page for a post that has been edited, which I just coded:
This is available via a link beside the 'Edited by' text on a post. Only moderators (those who can edit other people's posts) have access to it. It shows all previous versions of the post (in this case, there were only two versions).
One possible use for this feature is so that staff can find out if a student posts something offensive, then edits it 20 minutes later, before they get told off but after they've offended someone! Hopefully not a very common occurrence with OU students, who I'm sure are always exemplary in their behaviour... although I was vaguely considering signing up for a course, in which case that will obviously change...
[The feature can also be useful if there are multiple moderators, so that one moderator can check to see what another moderator did, etc. Or for answering 'what on earth happened to this conversation?' questions if somebody edits a post to remove a section which people have already replied to. And so on.]
Old versions of edited posts are optionally deleted after a time limit, by default 30 days. We probably won't be enabling that feature at the OU.