Google are testing out Adwords for mobile phones, called Mobile Ads:
“Mobile ads are shorter text-based AdWords ads that appear when users search Google from a mobile device. Send users to your mobile web page, or offer them the option to connect to your business phone after clicking on your ad.“
The available countries are United States, the United Kingdom, Japan, and Germany. Apparently, it works much the same way as Adwords, in that you choose a maximum cost-per-click for each keyword, but smart pricing does not apply
More at SEW and Clickz.