Two and a half years after Mark Zuckerberg floated the idea on a podcast, and several months after organizers said it would be ready to hear cases, Facebook’s independent Oversight Board is now up and running. In a call with reporters today, the board’s co-chairs said that they are now prepared to hear appeals from the billions of people who use Facebook and Instagram each day. The ability to appeal to the board will roll out gradually around the world over the next several weeks. And when it’s complete, one of the bolder experiments in platform governance will have finally begun.