I had this happen. Greg and I had gotten bombed off of the N. Face of Edith Cavell and the NE buttress of Howse in the C. Rockies, and we were getting annoyed and decided to redeem our manhood we would on sight a big moderate classic (E. Ridge of Temple) with the rope, rack and Gore Tex on the back thing, even though this is considered a very long day. One tool each and no screws for the snow/ice sections. Then we got near the summit ridge and the exit gully slid right in front of us, leaving several hundred feet of blue ice. Screwed. Time to go down, a long way. Got to a ledge about 1AM with no obvious non risky rappels and decided to hunker down. With nothing. It was fucking cold. I was mildly shivering when it got light because every thing had shut down to retain heat in the core, but when I started moving the blood from the limbs started circulating and I collapsed from the cold, shivering violently and really non-functional. It was a very strange sensation.