On 20/07/2011 the official notification from adsense blog.
Quote :
If you use a Custom Search Engine to power search on your site, you may already be familiar with the advanced Custom Search Element launched in 2009. Since then we’ve improved the results pages of these search engines with new features like mobile compatibility, more layout options, and new ad formats. We’re excited to announce that we’re now also taking steps to update the look and feel of traditional Custom Search Engines that embed results in an iframe on publisher sites, or that host results pages on Google.
Over the coming months you’ll see changes in the presentation of your search
results pages for a richer, cleaner, and easier to use experience for your users. If you monitor the earnings from your search engine through AdSense for search, you may also see changes in your ad performance. We’re working towards improving ad relevance for users with new layouts and ad formats, while continuing to prevent accidental clicks. No action is required on your part for these updates.
results pages for a richer, cleaner, and easier to use experience for your users. If you monitor the earnings from your search engine through AdSense for search, you may also see changes in your ad performance. We’re working towards improving ad relevance for users with new layouts and ad formats, while continuing to prevent accidental clicks. No action is required on your part for these updates.