Hackers have sacrilegiously put the AndroidOS 1.6 on the original iPhone, creating a Frankenstein device that will boot older versions of two of the most popular smartphone OSes.
You’ll need an original 2G iPhone and a 60+ step process and be willing to risk bricking your jailbroken iPhone, but the reward is that you’ll be able to dual boot your iPhone into Android 1.6.
This shows that, underneath all of the branding and industrial design, iPhones and Android devices are similar in architecture and based on compatible ARM chip designs. It will be interesting to see if newer versions of the iPhone can run newer versions of Android. Or perhaps some hacker can do the reverse and put the iPhoneOS on an Android phone.