I found this in the comments on Cabel’s blog. He’s on his 5th Xbox 360.
By the way, it’s not a single “Red Ring of Death” error. The three red LEDs signify many different possible failures (hardware, firmware, and software). If you hold down the binding button on the console and press the eject button four times, you can read out a more specific (undocumented) diagnostic error code.
Never would have known that if I didn’t have the intertubes.