According to Google’s Checkout page: “users click on ads 10% more when the ad displays the Checkout badge”. Google specifically writes that conversions will increase by 40% and the click-through-rate on your ads will increase by 10%. Furthermore, Google quotes one advertiser, Fred Lerner of Ritz Interactive, saying the Checkout icon has given them “a 23 percent lift in clickthrough rate.”

Source:→ Google Blogoscoped