Google today introduced Page-level ads in Adsense ( Currently active only for premium publishers and selective accounts ). This segment comes with two ad formats for mobile responsive websites. Once your accounts gets active for page-level ads you will get a notification on your google adsense dashboard. See how to activate tutorial if you got the notification already
Anchor/Overlay Ads in google Adsense
This type of ads will stick to the edge of the web page and can be dismissed very easily. As of now on test runs i have seen that only on bottom side of the pages.
These type of ads appear in between page transitions. These type of ads are also only for mobile responsive websites and found to appear only on usage on a mobile browser.
Before implementing google has given a comfort of previewing the actual working of both the ad-formats on your website with the help of preview tool. Once the page-level ads is active on your account visit your website url along with #googleads to see the preview for eg: if your webpage is http://www.shyamachuthan.com/index.php you can preview the page level ads by hitting http://www.shyamachuthan.com/index.php#googleads on your mobile browser ( provided you have a responsive website ).
Note: Currently this feature is available / introduced only for Premium Publishers / Selective Publishers, hope that will be available through out all google adsense accounts soon.
See Tutorial on how to activate pagelevel ads on google adsense