We just introduced two new features available now in the premium plans:
You can now organize your boards more precisely by adding a level of hierarchy inside your boards. Need to sort bookmarks inside a board by UI elements (Header, Thumbnails, Checkout,..)? It's now easy to do by creating nested board for each type.
If you are a Slack user, you can receive notifications from your collaborative boards in a Slack channel: when something new is added, when someone leaves a comment, or when a collaborator joins a board.
Read more about these new features Here