A few weeks back, a Google Wallet vulnerability was found making both rooted and untampered devices with the application vulnerable to hackers. The crack exposed the PIN within seconds, and was since temporarily patched by Google. This patch disabled the use of prepaid cards, and since then we hadn't heard much on the subject. Google is pushing three security fixes today that not only allow for prepaid card usage with Wallet, but offer core system fixes.
This update will also provide fixes to rewards card syncing in Wallet, and should increase stability in Google+ and Authenticator applications. Google Wallet had been considered insecure for months, so we'll just have to wait and see if this update will block out those hackers for good. If you were one of the many that installed the Google Wallet .apk file to your Verizon Galaxy Nexus, the update will not be visible in your Android Market.
However, you'll still be able to get the update - it will just take a little extra work. First, head over to http://market.android.com in your Android browser and search for Google Wallet. Next, just select install and sign into your Google account. After signed in, tap the back button until you are prompted to select "Market" or "Browser". Select "Market" this time and you should be good to go.