Up until now, no one really had a use for the Near Field Communication, or NFC, chip inside the Google Nexus S. It was a novelty that looked good in demonstrations, but lacked a practical use. Today, in an attempt to change that, Google demoed a system called Google Wallet that will let people replace their wallets with the Nexus S. The company is in the process of field testing Wallet and plan to release it "soon."
There are a few things you need to do in order to take advantage of Google Wallet. First you need to install the app, which will manage payment methods. Currently, only Google Prepaid Cards and Citi MasterCards are supported, but other cards should be added soon.
Next comes the difficult part: finding a merchant with hardware necessary for NFC payment. Google has partnered with retailers such as American Eagle, RadioShack, Subway, Walgreens, and others in an attempt to spread its system, and existing PayPass hardware will be compatible as well. However, it will probably still be a while before you can pay with your phone in the majority of stores.
Security is one of the major concerns about this system, and rightfully so. Because your debit or credit card is now connected to your phone, thieves could potentially wave a device near your phone and charge you money. Google has attempted to alleviate this issue by requiring you to enter a PIN every time you make a payment, but this is a solution for only the first of many potential exploits.
Even if it is not yet ready to completely replace your wallet, Google Wallet is still a cool application of NFC technology. With time for manufacturers to deploy point of sale hardware and Google to secure the service, it could become quite appealing. I know that I would like to be able to pay with simply a wave of my smartphone.[Google Blog]