Google says the Google Wallet app is more secure than a credit card.
A theoretical hack to the Google Wallet application on Andoid phones led Google to temporarily shut down the service while the strengthened its security. Google

According to a blog post written by Osama Bedier, vice president of Google Wallet and Payments, the company has repaired a weakness in the Google Wallet app that would have allowed anyone who picked up an Android phone with the application on it to make purchases with the original user's credit card. According to Bedier there have been no reported abuses of Google Wallet, and the application, which was taken offline after several possible hacks were pointed out, is now available again.

Google Wallet, for those unfamiliar with the application, allows users to pay at certain stores simply by tapping their phones against a payment terminal, after entering a pre-selected PIN code. According to Google the application is more secure than using a regular credit card, however, last week two different theoretical hacks were pointed out. The first is relatively difficult to do, but the second simply requires resetting the application and choosing a new PIN. Anyone who found a Google Wallet-equipped Android phone with no screen-lock could use it to make their own purchases.

In response to the news, Google temporarily shut down the application, which is still only available on the limited number of phones that are NFC (Near Field Communications) equipped. Google has fixed the problem for the time being, and is looking towards the future, in which they believe the majority of monetary transactions will be conducted with smartphones.

Mobile payments are going to become more common in the coming years, and we will learn much more as we continue to develop Google Wallet. Bedier wrote. In the meantime, you can be confident that the digital wallet you carry provides defenses that plastic and leather simply don't.