Apple announced the free iCloud service today, which stores content for iPhone, iPads, PCs and Macs. When anything changes on one of the devices, all of the devices are wirelessly updated. Services include Backup, Photo Stream, iCloud Storage and synching of apps and books.
iCloud Backup automatically and securely backs up iOS devices to
iCloud daily over Wi-Fi, while charging an iPhone, iPad or iPod touch.
Backed-up content includes purchased music, apps and books, Camera Roll
(photos and videos), device settings and app data. When devices are replaced, files are replaced from the cloud.
Photo Stream automatically uploads the photos you take or import
on any of your devices and wirelessly pushes them to all your devices
and computers
iCloud Storage stores all documents created, using iCloud
Storage APIs, and automatically pushes them to all your devices. 5GB of storage is included in the storage service. Storage required by Photo Stream doesn't count towards this 5GB total.
The App Store and iBookstore now download iOS apps and books
to all devices - not just the device they were purchased on.