If you've bought a popular music CD (you know, those plastic discs with music on them?) from Amazon over the last 15 years, you may now be able to download those MP3s for free via your Amazon Cloud Player. Amazon announced its new service called "AutoRip" on Thursday morning, allowing customers who buy AutoRip-compatible CDs to automatically receive free digital copies of their music. The policy not only applies to CD purchases since 1998—it applies to any AutoRip-compatible CD you buy from this point forward.

The MP3s come in 256Kbps form and are currently available for more than 50,000 of the most popular albums since 1998, "including titles from every major record label," says Amazon. The downside is that it may be difficult to find AutoRipped MP3s for indie titles, though a quick search by Ars revealed that several indie CDs (purchased in 2000) were indeed available via AutoRip. AutoRip-compatible albums are automatically uploaded to your Cloud Player library and don't count against the Cloud Player storage limits.

It's clear the goal of AutoRip is to push more users to take advantage of its Cloud Player service, in addition to pushing them to buy more physical CDs. The move undoubtedly allows Amazon and the record industry to double dip when it comes to sales and download numbers, but it's hard to deny the convenience to customers as well. Cloud Player libraries can be played on any device that Amazon supports—including iPhones and iPads—as well as the Web, or they can be downloaded and transferred to any MP3 player.

It's also clear Amazon is making this announcement to take a shot at Apple. "In many cases, customers can buy an AutoRip CD, including the free digital copy, for less than they would pay for only the digital album at iTunes," the company said in a statement. Indeed, Amazon, but then I would have to store all those CDs somewhere, wouldn't I?