Someone has just created a Virtual Boy emulator for iOS that runs in 3D using Google Cardboard! The full project is on github and the source can be downloaded here: https://github.com/tomkidd/VirtualBoyVR-iOS
The emulator has adjustments for 3D width to compensate for different sized phones and can be used with wireless controllers. It can be sideloaded onto any iOS device, included non-jailbroken devices using a free Apple developer account.
For more information and the full story behind the emulator, check out the main post: http://schnapple.com/virtual-boy-emulator-for-ios-using-google-cardboard-vr/