Apple deleted the iCloud libraries of developers at the weekend as preparation for the public launch of iTunes Match.

Testers were told in an email last week that libraries would be erased at 10am US Pacific time on November 12. Beta testers are asked to disable the feature on all of their devices prior to that point. Though tracks on computers shouldn't be affected, Apple advised that users keep a backup of their music and not to delete tracks from their Macs and PCs.

This isn't the first time Apple has deleted iTunes Match libraries, but the note that this was to "prepare for the launch of iTunes Match" is new, and suggesting that the service will go live shortly thereafter.

At its iPhone 4S event in early October, Apple set the end of the month as its goal for launching iTunes Match, but that deadline came and went without any further announcement from the company. While options for iTunes Match have appeared on iOS devices and the Apple TV, setting up the $25-per-year service requires the as-yet unreleased iTunes 10.5.1 running on a Mac or PC.

Once available to the public, iTunes Match will allow users to upload their iTunes libraries into the cloud, then listen to that music on all of their devices. Apple originally announced iTunes Match last June at its Worldwide Developer Conference as a part of its iCloud online service.