PlanetScale, a cloud-based database service, now supports zero-downtime data migrations from existing MySQL databases. This is made possible by leveraging Vitess technology, allowing users to connect their database to PlanetScale as a replica and then switch over with no data loss or downtime. The process involves connecting the database, initial data copy, replicating changes, deploying the application, and finally switching to PlanetScale as the primary database. Throughout this journey, PlanetScale provides features such as secure passwords, query insights, and a web console for direct database querying, all powered by Vitess's Unmanaged Tablet technology. The service aims to simplify the migration process, allowing users to try it out and provide feedback for continuous improvement.