When a post is edited, the revision of the post should be monitored as well (and take notice of "rollback" edits) to ensure that the submitted edit applies to the latest edit, in keeping with what Jeff said re:
The larger edits should "win" in every case -- if you made a tiny edit, you suck and your edit should always be discarded in favor of the larger, more substantive edit.
So the algorithm should use the postid + the source revision to generate the revision "size" before applying the "larger edit" as the "winning edit" in keeping with what Jeff said before.
That is the request. This request really belongs to @markrages