Do you have an old iPhone 2G laying around doing nothing? Well, if you feel like installing the Android OS on the phone, you are in luck. In this blog and video, planetbeing has managed to get an Apple iPhone 2G to dual-boot the iPhone OS and Android OS. Most of the Android features currently work and the iPhone's hardware buttons remapped for Android.
In his video showing off his achievement, planetbeing says: "It's not really production quality yet. I'd say it's alpha quality. Um, but pretty much everything works." In his blog, he apparently includes the file needed to get this working on your phone.
Pre-built images and sources at http://graphite.sandslott.org:4080/pub/idroid/idroid-release-0.1a.tar.bz. Read the README. For generic openiboot instructions, there's plenty now that you can search for.
As for support for the iPhone 3G, it should be coming soon. However, the 3GS will take somewhat longer. With the work he has already done on this project, hopefully more people will contribute to get this project really cooking.
Image from AndroidandMe