when co-sleeping goes too far - I was watching a show on Discovery Health earlier today called "Toddler Trouble" (i think) - I caught the last 15 minutes or so. There was a couple with a 2yo and one on the way. The toddler had been co-sleeping, and they wanted to move her to her crib to make room for the new baby. They were taking her to a psychologist/psychiatrist because they could not get the kid to sleep in her crib - she was terrified of being left alone in the crib. She was at the point where she would projectile vomit because she was so upset. (They tried to leave the kid in the crib at 1 year and she wouldn't have it) The Dr. told the parents they just needed to leave the kid in the crib and let her CIO - they could go back in every 5-10 minutes and "comfort her" for a very short period, but they needed to let her wear herself out. The parents lasted all of 3 minutes - the kid was gagging, so they just gave up and put her in bed with them.
The only positive outcome of this story is that the parents decided new baby was going in the crib from day 1, cause there was no way in hell they were going to try and do this 2x.