No, this is referring to their app, Paper. These are notebooks printed straight from their app, using your art.

As an aside: See papers like "RockStock", "FibreStone", "Parax", etc, which are "made from stone" (80% Calcium Carbonate (CaCO3) and 20% non-toxic HDPE.)

EDIT: Here's a wired article (http://www.wired.com/design/2013/02/stone-paper-notebook/)

In this case "Paper" refers to the name of the app that you can order these notebooks from, Paper: http://www.fiftythree.com/paper

This is my only criticism, the vernacular and wordplay on the website is sometimes confusing. Having made it through, I'm definitely interested in their product though.

To assure consumers that it's not actually made of mole skin, despite the spelling in the headline.