All he has to do in order to get the currency into circulation is first give advertisers a discount when paying with said coin, then integrate ecommerce for pages and "buy now" buttons that are connected to a user's wallet. In said wallet, the user can store Facebook Coins AND tethered fiat, then use them to pay for products and services (like an ad-free account on Facebook). This virtual wallet can then be easily integrated into Facebook apps and games, and basically the whole Facebook ecosystem. Zuck already owns the planet. Now he's just showing off.