It is a product that was developed by Zong, a company that PayPal acquired a couple of years ago. It is, as far as I know, only offered to digital merchants like Blizzard, Zonga-like games and so on. It makes it possible to technically add any payment method out there (Bitcoins, Credit cards, gift cards, SMS payments) as long as it is implemented first, and as far as I have heard they are really good at quickly integrating new payment methods that are requested.