Google Adsense is now available for Mobile websites, today when i logged in to my adsnese account i noticed a link to . You need to have a mobile website in order to use this adsense feature.
“AdSense for Mobile will be available in the following countries: US, England, France, Italy, Germany, Spain, Ireland, Russia, Netherlands, Australia, India, China, and Japan (available in the coming weeks).”
Official Google statement:
As part of our ongoing efforts to develop new ways for users to find the information they need anytime and anywhere, Google announced today the availability of AdSense™ for Mobile, a program that contextually targets ads to mobile website content. AdSense for Mobile also allows AdSense publishing partners the ability to earn revenue from their mobile websites through the targeted placement of mobile text ads. With this program, advertisers can connect with the growing number of mobile publishers, ultimately providing users with an enhanced mobile experience that helps them find what they are looking for more quickly and efficiently on the go.
So now the task is to optimize tour websites for mobile browsers and get paid with Adsense 
Update:
Ad Formats:
Even i noticed it today . Got any tips on optimizing the sites for mobile phones ?
@Madhur
Thanks for asking, i will publish some tips later today