Next month on February 8th and 9th, there will be the first ever "Doc Sprint" for WebPlatform.org. WebPlatform.org was launched a few months back to create an open documentation platform for web standards. This isn't tied to any particular browser vendor and includes representation from the W3C, Microsoft, Google, Mozilla, and Adobe. A Doc Sprint is much like a hackathon but instead of building the next big app the focus is on writing documentation instead.
The event will be held in Berlin, with an exact location being decided soon. (All folks who register will get contacted of course.) You may register here:
And visit the Lanyrd page here: http://lanyrd.com/2013/wpds/
Finally, you can read more details here: http://klick-ass.com/events/first-european-web-platform-doc-sprint-february-8-and-9-in-berlin/