There can only be so many good reasons as to why someone would feel compelled to do this, but apparently, some ingenuitive hackers have managed to get Android 2.3 Gingerbread ported to an iPhone 3G.
After several weeks of work, Nick Pack and others have found a way to install the Android OS on an iPhone 3G, using the OpeniBoot software that has been used on previous ports. OpeniBoot is an open source implementation of iBoot for iOS devices, which allows booting of unsigned code, such as Linux kernels, on the device.
Video of the action can be viewed HERE.