You are currently demoing the latest version of mapchat. If you are looking for the earlier version, from the book Getting Started with GEO, CouchDB and Node.js you can find it at v1.mapchat.im and the source for it on github.

The new version of map chat, supports multiple rooms, editing geometries, and of course chat. It is built with XMPP, Node.js, and strophe.js. The source for the new version is on github.