We knew it was coming and Apple has announced iCloud and it will replace MobileMe, and will sync and backup a wide range of things with your iOS device including purchased music, apps and books bought from the iBooks store.
It will sync your photos and videos from the camera roll as well as app data and your iOS device settings, plus documents from iWork apps and other apps. When you change a document on one iOS device it will be synced with iCloud and your other iOS devices automatically.
The best new feature in iCloud is iTunes in the cloud, which will allow you to sync any of your purchased music with your iOS devices. There is a new purchased tab in iTunes on your iOS devices, if you click on the cloud button it will automatically download to your iOS device.