Facebook Launching Payment System?

In the next 6 to 12 months a large portion of social networks are going to open up their platforms to developers. As open platforms become the standard within social networks, what will differentiate Facebook from its competitors? I’m sure a number of things, but the next move? A payment system. I have had a number of people asking me about how to make money on Facebook. I have even spoken with a number of people that are in the process of developing e-commerce applications on Facebook.