28 contributers who took up tasks in 38 issues both at the sprint and working remotely, 32 inital patches and at least one contributer who had his first patch committed to Drupal 8 - that's just the figures from the Documentation Sprint at DrupalCon Prague.

What made it work?

• A clear, but restricted list of tasks. We worked on one meta-issue Updating or creating hook_help texts. The tasks were varied - from reviewing existing texs and changing all links to the new routing format to complete rewrites but had core skills in common. My explanations were, therefore, not only relevant to one person at a time, and contributors could help each other. Once somebody had finished a task, they could move on to a similar one.
• Working from the meta-issue - a list of all 60 core modules whose hook_help texts need checking, updating, writing or re-writing - meant that there was a lot to choose from without getting lost in the full documentation issue queue.
• Some good resources: the meta issue; the standard help text as an example of how text should be written and coded; the section about thenew link format; the excellent help pages on drupal.org on how to create patches and interdiffs. All these - old school - listed on a flipchart made them directly accessible to everybody who joined us in the sprint room.
• Drupal mentoring: Cathy (YesCT) had organized an amazing team of mentors to help new contributors find appropriate tasks and get them set up with a development environment. Previously organisers felt that the documentation table became the place where people would drift who are not sure what they can contribute or how to get started. (I was one of these lost souls at the first sprint I attended myself...) This time nobody who joined us looked lost. Instead everybody was motivated and ready to go.
• The mentoring task list: I added some of the tasks into the task list for mentors to give out to new contributors. All of them were taken up during the sprint, or even before that.

And now?

Most issues still need review and possibly more work before they can be committed - a task that should be done sooner than later to keep the momentum.
But judging from the flury of activity in my list of issues: That's already happening.
And last but not least: A big thank you to every body who participated and made this possible!