iTunes Match allows iTunes users to create a music library on Apple’s servers through iCloud and software that scans your hard drive. That software creates duplicate copies of songs that are available in iTunes on iCloud, which means you don’t have to spend hours uploading the files to Apple’s servers. It costs $24.99 a year for this service, but it’s a much faster way to get up and running with a cloud-based music system than the music lockers offered by Google and Amazon.

Apple was overwhelmed in the first few hours the service was available, telling those who had downloaded iTunes 10.5.1 that “new iTunes Match subscriptions are temporarily unavailable” and to check back later in the day. During an event in October to launch the iPhone 4S and iCloud, Apple promised that iTunes Match would be available by the end of that month, but missed that deadline. The new software can be now downloaded here.

And in competitive news, Google is scheduled to hold an event on Wednesday that will likely see the launch of its own online music service after years of negotiations with the music industry.