Before it was quickly removed from Amazon’s pages, some hawk-eyed users spotted a landing page for a service called “Kindle Unlimited” floating about in the wild.

According to a web cache, Kindle Unlimited will offer over 600,000 titles and “thousands of audiobooks” on any device for $9.99 per month.

GigaOm also points to an active page with results for a “KU test” which lists 638,416 titles and 7,351 ‘Whispersync for Voice’ titles.

This shouldn’t come as a huge surprise, considering we heard reports last months that Amazon was currently in talks with publishers about a subscription service.

Of course, Amazon already has a sort-of subscription ebook service – their Kindle Owners Lending Library, which is free for Amazon Prime members.

The 600,000+ titles available in the Kindle Unlimited test mainly come from Amazon’s own publishing arm and the ones available through the lending library. It doesn’t look like major publishers like HarperCollins or Simon&Schuster have their titles available on the yet-to-be-officially-revealed service, however.

If Kindle Unlimited does in fact go live, Amazon will at least have a foot in the door with every major form of subscription-based media – movies and TV with Prime Instant Video and Music with the newly-unveiled Prime Music.

Image via Google cache