So far, we have successfully ported a customized uClinux (http://www.uclinux.org) kernel to the iPod, and written a simple user interface for it dubbed podzilla. Many additional Applications have been written, adding many capabilities not found in Apple's firmware.
Our bootloader allows for you to choose between either iPodLinux or Apple's firmware each time you turn on your iPod. iPodLinux is currently safe to install on 1st, 2nd, and 3rd generation iPods.
We are currently accepting Donations towards the purchase of a fourth generation iPod for us to test with. The fourth generation click wheel, mini, U2, Photo, and Shuffle iPods are NOT currently supported. For the latest information on 4th gen development, read the Fourth Generation Project Status.