Yup - I have had kids in care who just 'needed' to do this ... it generally lasts 2 -10 minutes depending on the kid and than they are asleep ... their self soothing mechanism - not my cup of tea.

My newest one his mom said she did not want him to CIO in the crib - during the transition period she would rock him to sleep but he still SCREAMED the entire time and then out like a light and she would transfer him to bed ... well seriously if he is going to CRY when you hold him anyway what the hell is the difference to just putting him down in the bed and keeping him company with a 'shhh' and a back pat for a minute or two ... which is what I ended up doing and to be honest he cries LESS that way and goes to sleep faster for me than trying to 'rock' him to sleep....but dude ALWAYS cries first before falling asleep even in the buggy or the car