I just saw the message in the image above on the Google home page offering users $10 to use Google Checkout. This is an interesting tactic to increase awareness of Checkout as well as showcase some of Google's key commerce partners.
I am personally torn on using Checkout. I understand the concept and the reason Google is trying to succeed where other giants have failed (read MS Wallet). I do hesitate to use it though as I am comfortable with the vendors I buy through online and this would mean that Google has access to my credit card and address info. That's one of the reasons that MS Wallet failed in the first place. Why would someone use this service over going to Amazon?