Google has entered the online payment business with Google Checkout, but has not had much luck unseating erstwhile leader, PayPal. Now its Facebook entering the game. They look like they are more of a niche player who want to take advantage of their large registered user base to sell stuffs to each other.
And what's up with PayPal's new new API that is getting a lot of market buzz? Initial released documents show that its somewhat similar to Amazon's system. Initially called Adaptive Payments, it allows payment to be cascaded down a chain and allows a single payment from a customer to be "split up" to pay multiple suppliers. This can be useful if, for example, a shopping cart contains items from multiple suppliers.