Facebook has been in the process of testing their new payments system for the past few months and recently reached out to the developer community to request inquiries from those application looking to use test the new system. According to Facebook there are now 8 Facebook applications that are accepting Facebook Credits. The process of using Facebook Credits is fairly straight forward. Users of an application are given the opportunity to make a purchase for upgraded features or for virtual goods and then are prompted to checkout as pictured below.
Facebook has been testing out the system for a few months and now has integrated with the following applications: