Robert Scoble discovered purple numbers, the usually purple coloured permalinks for paragraphs. I was too fast commenting:
The idea is very good, but as you say, nobody is going to do this manually, and in all those months (years?) since the original idea, nobody implemented it in any CMS.
I got corrected immediately by David Winer, who’s site has a very good implementation of purple numbers, using the edit time as an anchor to make sure each permalink is unique.
Another comment pointed me to a WordPress plug-in, which of course brings the question: Did anybody make a plugin for Movable Type?