In their own words...
Since we recently launched the ability to use any debit or credit card in Google Wallet, we are going to discontinue the Google Prepaid Card soon.
Spend your Google Prepaid Card balance
To check if you have any funds remaining on your card, navigate to the Payment cards section of the Google Wallet app and tap your Google Prepaid Card.
You don’t have to spend the exact amount of your balance — at most merchants, you can cover the remainder of a purchase with any other payment method.
Important dates affecting your Google Prepaid Card
September 17, 2012: You will no longer be able to add funds to your Google Prepaid Card or add a new Google Prepaid Card to a new device. Please be aware that resetting the Google Wallet app after this date will remove the Google Prepaid Card and you will not be able to re-add the card. Find out more at http://www.google.com/wallet/prepaid-refund/faq.html
October 17, 2012: Your Google Prepaid Card will disappear from the Google Wallet app and you won’t be able to spend your balance any longer. Don’t worry, you will be able to request a refund if you have remaining funds by visiting www.google.com/wallet/prepaid-refund.
This won't affect a lot of readers in the US, but for those of us in unsupported territories that were enjoying trying out NFC payments, it's a bit of a shame.
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