Apple today released a Mac-only beta of its upcoming iTunes Match service--an optional and paid part of its broader iCloud effort--to registered iOS developers. (I assume a Windows version is coming soon.) Apple previously announced iTunes Match (and iCloud and iOS 5) at its June Worldwide Developer Conference (WWDC), stating that it would be available publicly by the end of the year.

Since then, Apple has released several pre-release versions of iCloud, iOS 5, and iTunes 5.x to developers, but this is the first time anyone outside of Apple has gotten their hands on iTunes Match.

So what is iTunes Match? At the WWDC event, then-CEO Steve Jobs described it as the final piece of its "iTunes in the cloud" services, part of iCloud. The company provides a number of iTunes-related services in iCloud for free, but iTunes Match is a subscription service costing $25 a year. It completes the picture on "iTunes in the cloud," so to speak, by adding a matching service that examines the digital music in your collection that wasn't purchased in the iTunes Store and providing you with cloud-based versions of much of that collection. These cloud-based songs are in high-quality, DRM-free, 256 Kbps AAC format as well.

Other cloud-based music services, like the Amazon Cloud Player and Google Music Beta (both of which I'm currently testing you) allow you to (or, in Apple's view, "require you to") upload your entire collection to the cloud arguing that this is time consuming. (I'd counter-argue it's a one-time upload, and both times I did it with these competing services, it took only a few hours.)

Apple has over 18 million songs in its iTunes Store right now, so there's a pretty good chance they'll have most, if not all, of most people's collections. And there is certainly some advantage to getting new, clean, copies of those already-ripped (or potentially illegally downloaded) songs. Some have argued that iTunes Match is essentially a recording industry-supported indemnification of sorts, allowing those with less-than-legal collections to go legit, as it were.

Regardless of any of that, iTunes Match looks very interesting. And even though I've legitimately ripped my own CD collection and have since been purchasing music from legal online stores like iTunes, Amazon, and Zune, I'm very curious to see what a clean, iTunes Match version of this collection looks like.

I can't currently evaluate iTunes Match or even describe my experiences yet. But I will as soon as I can.