I really wish the system would flag edited comments. I have edited comments all the time do to my incredibly poor spelling and grammar but also to update and since I never see an update I feel the need to put like EDITED - with the update and while I still might do this for major things just to break apart the initial and the update I still would like an automatic tag so I don't feel the need if its more minor. What would be awesome would be to see something like the track changes type of thing in a text document with the crossed out words and stuff. Like if you could choose a drop down that would give that view.

Yes it saves the original comment body.

Due to the way federating works, a lot of regular users across different servers and clients will see the original content for quite a while too.