Yesterday Google released AdMob Windows Phone SDK Beta for download. The SDK, which includes HTML5 support, allows developers to "easily integrate advertising into their applications, control where the ads appear, and what types of ads are shown in their apps." Text and banner ads can be linked to websites or directly to the Marketplace. The SDK maintains the same look and feel as WP7 and allow users to click on an ad, then smoothly return to their current application.
AdMob WP7 SDK can be downloaded by current AdMob members by logging into their account and adding the Windows Phone 7 site type. Google has also updated their iOS and Android SDKs to include new features, such as enhanced HTML5 support.
Source: Google Mobile Ads Blog