iTunes Match stores your complete music library in iCloud, allowing you to enjoy your collection anywhere, anytime, on any iPhone, iPad, iPod touch, or computer.
iTunes Match beta is currently available to developers in the United States. Beta subscribers will receive iTunes Match service during the beta period plus an additional 3 months for free with their 12 month paid subscription.
To get started with iTunes Match, devs simply download the current version of iOS 5 beta and iTunes 10.5 beta 6.1 with iTunes Match. Once installed, choose Turn On iTunes Match from the Store menu, and click “Subscribe for $24.99.”
Developers are told to maintain a local backup of their iTunes library as well as any music added to iCloud. Apple will periodically reset your iCloud library during the beta and it is critical that devs backup their music regularly. Some features and optimizations of iTunes Match will not be available during the beta.