Post Lock: WordPress 3.6′s new feature in the editor
Post Lock will allow authors to lock their post so that other authors cannot access it or work on the post at the same time.
This will be a welcome relief for people who have or work on a WordPress site that has multiple authors. You will still be able to access the post, but will get a message saying that you can ‘take over’ or ‘go back’.
LOOK FOR IT WHEN YOU UPDATE YOUR WORDPRESS SITE TO VERSION 3.6 You can also read more about this and other upcoming features over at WordPress.org