Google announce the launch of their shopping cart a few days ago, its called Google Checkout Store gadget, its and API of Google checkout. You can not use it with any other payment gateway nor can you use it without signing up for Google Checkout.

It claim to help you get your store online in under 5 minutes but you have to use and all Google tools to from start to finish, first you use Google spreadsheet doc to upload your product or to use the Google step by step guide:

1. Signup for Google checkout account
2. . List the products you want to sell in a Google Docs spreadsheet.
You'll just need to create a copy of our template spreadsheet, and then replace the sample inventory with your own.
3. 3. Place the Google Checkout store gadget on your website.
You can embed your online store anywhere you'd like -- on Google Sites, Blogger, or your personal website.