Google Adsense is testing change in link background colors on mouse hover over the links. This new ad unit variation definitely helps to highlight the ads.
Normally Adsense publishers can choose to decide the background of their ads. We have 336×280 ad units on our pages, with a white background set, and a light green background is visible as you hover over the ad. However, the clickable area is still the ad title and link url. The mouse over the title also reveals the destination url overlapping the ad text.
When you hover over to the next link the background of that link changes.
Google adsense routinely tests many new ad variations, which if work, become standard features, else a new variation is tested. Check out some cool ad variations they tested before twitter ad units, 2×2 ads, favicons, no titles, favicons, checkout icons, titles in italics, multiple languages, no Ads by Google and interactive keywords.
What are your thoughts on these new ads? Do you seem them on our site or your site?