OwnCloud version six was released last week, and part of the release was a pretty major new feature: real-time collaborative editing of ODF documents (the format used by Libreoffice, Calligra, etc.). Although Etherpad has supported collaborating on simple text document for a while now, this is the first Free Software equivalent to Google Docs. From the article: "WebODF is a javascript library that lets you display ODF files in your browser. Think of it as PDF.js, but for ODF. You just throw a webodf.js script on your server, and do a couple of javascript calls to render an ODF file. It works completely client-side, no serverside ODF processing required. ... The collaborative server, included with OwnCloud Documents, lets users join a 'session', which is basically a document with a history of edit operations. Operations are small units of edits (think 'commits'). In a collaborative session, we use Operational Transformation techniques to make sure that operations fired by various clients will eventually result in a consistent state everywhere. When a new client joins an existing session, all earlier operations are played-back for it to reach the current state. Note that this editing is not turn-based; this is true inline collaborative editing where users can join a document and start editing straight away." As always, source is available.