[XanTium] passed this along to me, and did a nice job of writing it up. You’ll still need those old kernels, but here’s the scoop:

“A modified Gentoo LiveCD and new KingKong Shader Hack have been released for the Microsoft Xbox360 console that will allow you to boot Linux on your Xbox360 pretty easily! The new shader hack no longer requires a serial connection on your 360 and will load the XeLL bootloader directly from DVD. Once the bootloader ran you can insert the ‘Xenon’ modified Gentoo Minimal 2006.1 LiveCD and run Linux. As this hack uses the Hypervisor Vulnerability it will only work on Xbox360 consoles with kenrel 4532 or 4548 (downgrading is not possible at this moment as Microsoft blew-up eFuses in CPU to prevent kernel downgrades), to run the shader hack you’ll need the Xbox360 King Kong game (modified with thew new shader patch mentioned above) and to run this modifie d game disc you’ll need to flash the Xbox360 DVD-ROM drive with a modified firmware.”