A first generation Apple iPhone running the Linux kernel and Google's Android mobile operating system.

Here is a video of iphone running Android on it.  Here is a comment from the author

It should be pretty simple to port forward to the iPhone 3G. The 3GS will take more work. Hopefully with all this groundwork laid out, we can make Android a real alternative or supplement for iPhone users. Maybe we can finally get Flash. ;)

he published the code too, so read more here

[Via Sizlopedia]