I did manage to write this thing, sort of, in 2 hours. You can see it in action here: http://tinyurl.com/locche1 and it has some rather unusual features :-)
You can hack Locche inside Locche.
You can go back to previous versions of the text (or Locche) from any copy of Locche
It uses no server whatsoever (other than a CDN to get JS and codemirror)
Making it pretty
Shorten history URLs so the size doesn't explode so much
Fix handling of ' " and probably other characters in the text
But I think it's cool. Below is the liveblog of how it was done. Have fun matching it with the commit history at https://github.com/ralsina/locche
I am going to live-code a pastebin, with a few twists.
It's called Locche, in honour of Nicolino Locche, The Untouchable.
This page will update every 5 minutes until I am done, or 2 hours have elapsed.