During the keynote address at its WorldWide Developer's conference, Apple today provided details about what iPhone users can expect to see in its new iCloud service. iCloud is a completely re-written version of Apple's MobileMe concept and it works across all iOS devices. All content on a users' iOS device is backed up in iCloud, such as calendars, email, contacts, applications, and books. Changes made on one device are (eventually) reflected on al a user's iOS devices through automatic syncing. iOS devices will update automatically (via Wi-Fi) each day, including music, books, apps, photos, device settings, and application data. Apple calls the photo-syncing support Photo Stream. Photos will be automatically uploaded to iCloud and synced to a user's other iOS devices. They can also be reached from the AppleTV for sharing on TV sets. Apple will store the last 30 days' worth of photos online, the last 1,000 photos on the device itself, and all photos on a user's computer. iCloud also integrates with Apple's productivity software, such as Pages, Keynote, and Numbers. All will be automatically backed up in iCloud when changes are made. The idea is to make all of a user's documents available to them on any device no matter where they are. The biggest feature of iCloud is syncing with iTunes. Users will be able to purchase a song from Apple iTunes Store on one device and sync it across all iOS devices (multiple downloads for no charge). iCloud will have APIs for developers, as well, so they can take advantage of its benefits. Use of iCloud will be free for iOS devices.