(Update 12:15 pm ET: Facebook sent the following statement to AllThingsD after publication on Thursday: “We continue to have a great relationship with PayPal, and this product is simply to test how we can help our app partners provide a simpler commerce experience. This test does not involve moving the payment processing away from an app’s current provider.”)
This would be an obvious next step with the recent release (?) of facebook's Reservations update. Make a reservation, throw a credit card down when you make it, No more waiting for the bill to come out; The restaurant just charges your food to the card you made the reservation with.
(Update 12:15 pm ET: Facebook sent the following statement to AllThingsD after publication on Thursday: “We continue to have a great relationship with PayPal, and this product is simply to test how we can help our app partners provide a simpler commerce experience. This test does not involve moving the payment processing away from an app’s current provider.”)