We started out with 5 caterpillars; 3 were healthy and happy and we set them free to live on their own; 1 was sadly damaged by a curious 4 year old and so he remains with us for the remainder of his days; 1 had problems and so never successfully hatched out of his chrysalide. It's been interesting and the kids have had fun. I'm not sure if I'd do it again, though, because it's just so sad when things don't go the way you expect them too (sad for me - not necessarily sad for the kids)!
Here are the kids letting 2 of them go:
Check out the curled tongue on this one!
This is Limpy - he's the one that stays with us. He was originally just "hurt," but then eventually his wing fell off. Sometimes we take him outside to sit on the grass. Poor little guy (or girl, I guess!):