Amazon introduced today a new payment processing tool for mobile devices, called "Mobile Payments Service." MPS includes a set of application programming interfaces (APIs), which allow developers and merchants to offer payment options to their customers within mobile websites and apps. The new service supports Amazon's "1-Click" checkout for quick transactions.

Using MPS, customers can complete a transaction in four seemingly hassle-free steps. When a shopper is ready to pay, they click on a "Pay with Amazon" button, which prompts them to sign in and select a payment option on file with Amazon, and then they must authorize the payment.

Things are similarly easy for developers and merchants already using Amazon's Payments Service on their websites. The service will detect when users are shopping from a mobile device, and switch over to the new Mobile Payments Service automatically.

Amazon's new payment system has already been adopted by Handmark, a mobile content store which offers games and apps across various platforms including Android, Blackberry, iPhone, Palm OS, Windows Mobile , Symbian, and Java.