Apple has finally revealed iCloud at WWDC 2011. Steve Jobs defines this service as: "iCloud stores your content in the cloud and wirelessly pushes it to all your device. It automatically uploads it, stores it, and pushes it to all your devices." Managing content between our devices is never going to be the same again, thanks to iCloud.
iCloud will automatically store daily content such as your books, photos, videos, app data, music bought from iTunes and device settings via Wi-Fi. The Documents in the Cloud app will store projects that you make in the iWork suite and will sync it seamlessly across all your iOS devices.
PhotoStream is going to be a new gallery in the Photos app of your iOS device and will sync all the pictures that you take with Mac computers, other iOS devices, Apple TV and even Windows PCs. As soon as you take a picture on your iPhone, it will automatically be synced to other iOS devices, Mac computers and even Windows PCs as well as being stored in the cloud for 30 days.
iCloud will not be serving any ads to its users. iCloud is going to be offered free for all users and will be implemented in all devices running iOS 5. Users will get free storage of 5GB for contacts, mail and calendar. PhotoStream doesn't count.