Update: As was pointed out by9to5Mac readers in the comments, the update was zapping account data. Google says that it is aware of the issue and has removed the app from the App Store.
The Google Authenticator app for iPhone was updated this evening with an entirely new design. Version 2.0 introduces a host of visual changes, including the long-awaited addition of Retina graphics (which have been missing from the app since the iPhone 4 launched) and support for the iPhone 5. Even after the long wait for what seems like a relatively minor update, the app still does not natively support the iPad.
The app’s new look is based on the “cards” motif seen in other Google app releases recently. Most of the functionality seems unchanged.