Today they launched the developers mailing list for technical/serious discussions on how get Linux boot on the Xbox 360.
Their documention page also contains some interesting details about the Xbox 360 already:
- The flash is encrypted with a per-box key
- The key is stored inside the CPU
- The boot ROM is stored inside the CPU
- Also inside the CPU is a hypervisor that verifies the running state of the kernel, making sure there is no modification (RAM checksums), else the Xbox360 panics and blows up!
- The CPU contains RAM inside of it to store the checksums
- All interrupt/exception handling is done by the hypervisor
- All code runs in kernel mode
- The emulator for first generation games can be updated via an official Microsoft download burned to CD by the user, though the CDs' content will be encrypted and signed with public key cryptography.
The Xbox 360's Hard Disk appears to connect to the Xbox 360 via 7-pin SATA, internally the drive connects to the external connector through standard SATA data and power connectors. This should be of some help.
They also have a disassembly of the official Xbox 360 WirelessLan adapter (Marvell 88W8388-BDK1 which seems to be 88W88305-derived,) here. They tried to connect it to a linux PC, but no support for it atm (full initialization failed?).
Some info about those backward compatibility updates are available here.