I just came across this on the front page, and thought I'd add my experience (I've posted about it before under my old name).
CC didn't work for us. We tried when DS was about 18 months (I think - it's a long time ago now!). I was very unwilling (I had been very, very anti-CC) but he was still waking 6 - 8 times a night, every night, at that age.
So DH and I agreed to give it a go. And we did it by the book. Going in after 1 min, then 2, then 5, then 10 and so on. Never picking him up, just saying 'hush now, night night' and leaving again.
A bit like potatofactory's experience, he got more hysterical, not less. We did 5 nights, never deviating from the bloody plan. Each night he screamed and howled and sobbed from the second he was put down. The worst thing was when he would go quiet, and I'd leave it for 20-30 mins and then go and have a look, and he'd be standing in his cot, in the dark, watching the door without a sound. For half an hour. At 18 months old. Not lying down, not sleeping, just watching and waiting. Until he saw me, then he'd start to howl again. Each night he fell asleep, utterly exhausted, at around midnight, while I was in the room saying 'shush love, night night'.
On night 5, we realised this was hell, and we stopped. Those 5 nights made him frightened of going to bed, hysterical at bath time, and he clung to me all day for about a week.
I don't regret trying - it's a difficult pressure to resist, and almost everyone tells you it will work if you do it right. It didn't work for us and made DS very unhappy and scared.
We went back to co-sleeping to get enough sleep to function, and as time has gone on he has got better. At 2.3 he now wakes 1-2 times a night.
Things change over time. CC works for a lot of people, but not for everyone.