Starbucks is testing a mobile payment system in Seattle and Silicon Valley.

The Starbucks Card Mobile app allows users to add money to their card account from the app using a credit card, and then use it to pay for Starbucks products by swiping a 2-D barcode on the screen, writes the Seattle Times.

Another app tells users where they can find the nearest Starbucks store, along with other information such as which stores have drive-throughs. Both apps are free, and Starbucks is offering promos like free coffee and wi-fi to early adopters of the apps.

Starbucks said it has pondered what some might consider the Holy Grail of coffee applications: the ability to preorder and prepay from a mobile device and have a hot coffee waiting at the head of the lines. But a company spokesperson said the timing of such an application would be tricky, as customers would not want to pre-pay for a hot beverage that has already gone cold by the time they picked it up.

While mobile phone payment systems are not likely to catch on overnight, several key players are plotting possibilities for the future, reports the Financial Times. Nokia is integrating a payment system into its phones, while PayPal is planning a similar expansion. The FT points out that other iPhone apps have attempted to achieve in-store mobile payments, but required additional hardware for the phone.