The Xbox Linux Project has released the first full Linux distribution for the Xbox, a single CD version of Mandrake 9.0, available here. The Project has already produced various howtos and tools for the installation of SuSE and Debian on the Xbox (you'll still need a modded one, of course), but the Mandrake distribution is intended to simplify matters and, presumably, to broaden the user base.
Mandrake was chosen, according to the Project, for purely utilitarian reasons. Red Hat is "quite conservative with its package versions, and we wanted to provide the most modern distribution available." SuSE doesn't have a GPLed distribution download, and "Debian isn't the typical distribution for the end user, and besides, Debian for the Xbox is already available." They also say that of the four, they found Mandrake ran with the least modifications.
In order to install it, you need a modded Xbox, and a USB keyboard and mouse which you'll need to connect via a build-it-yourself USB adapter. The project has published instructions for this in the past, but last week also put up instructions for fitting a standard USB socket to an Xbox, here. So a little bit of soldering, then shove in the CD and you're there. It's really all starting to sound quite plausible. ®