Coming several weeks late, Apple has just now officially launched iTunes Match to customers in the United States. The iTunes Match launch is facilitated by the release of iTunes 10.5.1, which now allows users to subscribe to the $25/year service offering cloud-based matching and upload of users' complete iTunes libraries. iTunes 10.5.1 is available via the iTunes download page and should be rolling out to Software Update shortly.

Apple had apparently initially intended iTunes Match to launch by mid-October as part of iTunes 10.5 as seen in a number of developer betas, but the company removed the feature from iTunes 10.5 for the public release, giving it a few more weeks to complete work on the service. Even so, Apple missed its stated launch target of "end of October" and did not provide an updated timeframe for the iTunes Match debut once the target was missed, although the company continued testing with a new developer beta of iTunes 10.5.1 just this past weekend.

iTunes Match is a U.S.-only service for the time being, although the company is reportedly working hard to secure licensing to details to expand availability to other countries. iTunes Store users in a number of countries have been greeted with a "coming soon" tag on iTunes Match promo listings in their country-specific stores, suggesting that Apple is optimistic regarding expansion of the service in the relatively near future.

Update: Demand of iTunes Match subscriptions has overwhelmed Apple's systems, and the company has halted new signups for the time being.

New iTunes Match subscriptions are temporarily unavailable.

Due to overwhelming demand, iTunes Match is not accepting new subscriptions at this time. Please check back in an hour.

Update 2: Despite Apple's notice about overwhelming demand still showing on the iTunes Match subscription page, subscriptions do now appear to be going through.

Update 3: iTunes 10.5.1 is now available in Software Update.