A Google spokesperson confirmed today that the company is testing mobile AdWords in the US, UK and Germany. As reported earlier, the system is similar to the test in Japan, which began in April.
"We are currently conducting a pilot to test mobile ads in the US, UK and Germany," said a Google spokesperson. "This is similar to the pilot test we conducted in Japan late last year, and it is open to all advertisers in the US, UK and Germany. We will continue to evaluate the mobile ads pilot and will refine the product based on feedback from our advertisers and users."
The Google AdWords Help Center provides more information on the service. According to the FAQ, pricing is similar to the company's keyword bidding for regular Internet search. Smart pricing doesn't apply and conversion tracking is not available.