I like stuff like this. Have you considered real time collaboration? Your not to far off from this with something like web sockets.

Edit: realized it looks like the data is stored in the url, which is a neat approach but I guess its not really that close.

It's entirely possible to update the URL in browser without reloading the page.

Permalinks are needed to share documents, which would be something like a link shortener, with the target updating as the document is updated.