Apple this morning released a new version of iTunes that adds the company's new scan-and-match service for music.
iTunes 10.5.1 includes iTunes Match, a feature that scans a user's library to find music that wasn't purchased from Apple. If it finds a match in Apple's own Music Store library, Apple provides a user with a cloud-based version at the same quality they'd find if they bought it off iTunes--at least so long as they're a paid subscriber to the matching service, which costs $24.99 a year.
The feature made its debut at Apple's developer conference in early June, and has been in developer testing in beta versions of the music software since early August. Apple originally planned to debut it by the end of last month, but October came and went without any sign of iTunes Match or any explanation from Apple on its absence.
Over the weekend Apple hinted it would be launching the feature soon, after sending developers an e-mail noting that it was wiping out iCloud music libraries with matched tracks in order to "prepare for the launch of iTunes Match." Apple had made several of these purges during iTunes Match testing, as well as during testing for iCloud backups of iOS devices.
iTunes Match is integrated with Apple's iCloud platform, which taps into the cloud to do things like ferry files, content, and apps between Apple devices. In this case, matched tracks are effectively licensed to users, letting them download music tracks to a device, even if they bought them on another device. Apple has also extended the capability to its Apple TV product in a recent update, letting users listen to music from collection without storing it locally.
Update at 10:30 a.m. PT: Well that was fast. Almost immediately after offering the feature to users, Apple took away the capability to sign up for it. A message on the software notes that subscriptions to Match are temporarily unavailable and that users could "check back in an hour." Apple experienced similar growing pains in its early developer beta of the feature, which was closed off shortly after letting in a group of testers.