Beginning May 5, Google Checkout's fees will transition to a new tiered fee structure based upon a merchant's monthly sales processed through Checkout. While this new fee schedule appears to be similar to PayPal, Google's transaction processing rate will vary each month based on your prior months sales volume.
The new pricing plan will also eliminate the credit for Google AdWords advertising, discontinuing the processing promotion that was part of the original fee structure for Google Checkout.
Fees apply the same for Visa, MasterCard, American Express, and Discover payments. There are no monthly, setup, or gateway fees. However, for cross-border transactions, there will be an additional 1% fee assessed per transaction. To learn more about Google Checkout fees visit http://checkout.google.com/seller/fees.html.
Read more on The Official Google Checkout Blog.