I was quite surprised to see this new feature. The ad was in the normal place on the top right side of the SERP. (See attachment)
This has been live for almost a year now and is available in the US and the UK. I guess it is an incentive for AdWords advertisers to use Google Checkout.
The icon appears on adsense ads on the content network. The button appears on the US and UK search network.
This is a nice tip cianuro, but how about those who are based in Asian countries like me? Can't we get any options regarding this as it will surely give good hits to PPC management and earnings?