Google has introduced text-based Mobile Ads that appear when users search Google from a mobile device.
The users can either visit the advertiser's webpage on their WAP screens or there's an option to call the advertisers' phone after clicking the ad [something like Click-To-Call]
The service is currently available for mobile phone users based in US, UK, Japan, and Germany.
Now the Google ads on regular webpages can be removed by changing the Windows hosts file, don't know if there's any similar adblock extension for cellphones ?
Google Adwords Mobile Ads [Thanks Brian White]