At WWDC 2011, Apple has announced iCloud, the new digital hub to replace your computer as the center and make it just another device. Essentially iCloud is a way to revolutionize the way you sync your content and push it to the cloud so it can easily sync with all your devices.
This is completely integrated with apps and even has an iCloud Storage API. It works for Macs, PCs, and iOS devices. Pages, Keynote, and Numbers support Documents in the Cloud which allows you to edit a document on one device and have all changes synced to your other devices so you can grab your iPad and keep editing.
Your App Store purchase history can be viewed on all devices and contacts and calendars are synced as well. Along with these changes, MobileMe in its present form is gone and mail, contacts, and calendar are now free. iBooks will sync your progress between devices and keep everything in sync.
Photo Stream will allow your last 1000 photos to be synced instantly between all your devices and stored in the cloud for 30 days. All photos are stored to your Mac or PC.
The final and rumored feature previewed was iTunes in iCloud. Whenever you purchase music on any device or computer and the music is automatically downloaded to your other devices and computers instantly.
One surprise is that all of this is free. You have 5GB of free storage which covers mail, docs, and backups. Other data such as purchased music, apps, books, and Photo Stream don't count toward that 5GB.
The only part of this that costs anything is the new iTunes Match service which is $24.99 per year. iTunes Match will scan your library of music for ripped tracks and provide the same music as 256Kbps AAC DRM-free files for that one fee even if it is 20,000 files.
iCloud will be available this fall. Apple is very serious about this whole process with their new North Carolina data center. Apple emphasized how "Green" this data center is. This puts an end to the WWDC 2011 keynote address. Thanks again to MacRumors for live coverage.
The iCloud page at Apple.com should be up shortly since iCloud.com already redirects to apple.com/icloud.
Update: The iCloud page is now up.