[Editor’s Note: Facebook has been experimenting with Credits, its in-house virtual currency, for years. But now the company is looking at ways to get all developers on its platform using Credits (while it takes a 30% fee for the service). And given Facebook’s ambitions for the currency already, many people in the industry are wondering what Credits might become in the future. A “PayPal killer?” In other words, a payment wallet that can be used for any transaction across the web, if not in physical locations? That description makes for easy headlines, and there are reasons it could happen, as panelists at our Inside Social Apps looked at in April.