"Consolidated revenue for the fourth quarter was $2.69 billion, down $43 million or 2%, compared to a year ago on a $115 million decline in debit network fees. These fees are passed directly to customers and therefore did not impact operating income. Adjusted revenue, which excludes certain items including debit network fees, increased $47 million, or 3% year-over-year to $1.73 billion."
Interestingly, Facebook doesn't use the term "Facebook Credits" in the S-1, preferring instead the simple term "payments". Remember also that Facebook does a 70/30 revenue split with developers, implying that the $557M in 2011 payments-related revenue came from $1.867 billion in Facebook Credit redemptions.
On the web:
On the wires: