Xebian (aka Ed's Debian)
Xebian 1.1.0 - This is the most widely installed and distributed version of Linux for the Xbox. With superb flexibility and ease of use, it can run live off CD/DVD or it can be installed onto the Xbox hard drive in either the free space or the saved game area. The OS includes support for all versions of the Xbox, including those with Xcalibur video chips.
Based on Debian Testing (Sarge) with backports for newer software. http://www.xbox-linux.org/Download#Xebian_.28aka_Ed.27s_Debian.29
This archive will provide Debian packages for Xbox, from patched software to drivers and utilities. Currently the packages are only available for the woody distribution.
How can I use them?
Just edit /etc/apt/sources.list and add the following lines:
deb http://ftp.linux.pt/pub/xbox/debian woody main
Then do apt-get update and you're ready to go.
OpenXDK is an Open Source, Free, Legal Xbox Development Kit. OpenXDK is being developed to facilitate hobbyist and "homebrew" coding for the Microsoft XBox.