In a blog post on the Official Google Checkout Blog earlier today, Google introduced the Android Payment Extension - a way to allow mobile merchants to quickly set up a store and accept payments via Google Checkout and Android.
The post describes the steps involved - as a merchant you signup for Google Checkout, create a webstore, list the items for sale in a Google Spreadsheet, and install the Android Payment Extension.
Once you're setup, at a craft fair, for example, you'd create a cart on your laptop based on what the customer verbally tells you they want to buy. You then click on the Checkout with Android button and the customer scans the QR code on your laptop using their Android phone - which takes them to the buy page where they can complete the purchase on their phone.
Seems to me this is yet another example of using optical (bar codes and mobile phone cameras) to leapfrog the grid lock that seems to exist re: other connectivity solutions.