Three red rings for me today on my launch unit... the unit powered on, but none of the fans were blowing, and got nothing but a blank screen. Following the steps outlined at the beginning of this thread revealed an error code of 0020. Scary stuff.
With nothing to lose, I wrapped my 360 in a towel and let it simmer for about twenty minutes. Powered on, the fans went WHOOOOSSSSSHHHHH, and I was able to play again... I've had several successful power-ups and power-offs since then; who knows how long my fortune will last, but hopefully long enough for Microsoft to send me a 360 coffin.
Coincidentally, yesterday I had to turn on the air conditioner for the upstairs (which is where my home theater is); it gets me thinking that heavy use, followed by rapid cooling, does cause some of the solder/connections in the 360's guts to shrink and crack.