Co-sleeping is an integral part of attachment parenting. It is common knowledge that breastfeeding is the best food for an infant. However, breastfeeding is a lot harder when the mom and baby do not co-sleep. Peggy O'Mara, the editor of Mothering Magazine, writes a wonderful article in response to the idea that it is automatically unsafe to put the baby in the bed with the mother. In her article, Get out of My Bedroom!Ms. O'Mara makes a profound argument for co-sleeping using studies of entire societies that co-sleep and mother's intuition for hard evidence. Some people would say that a mother's intuition is false. However, I don't think that you can convince any woman who's been a mother for more than 4 days that it doesn't exist. Also, the article mentions that safety in co-sleeping is important. Just as people publish safety instructions for babies sleeping in a crib, people should publish safe co-sleeping practices.
I believe that if one takes precautions, co-sleeping can be even more safe than crib sleeping. When the baby is in bed with the mother, the mother can hear the baby's cues. If the baby does stop breathing or get stuck, the mother is right there. If the baby is in the crib in the other room, the mother is less likely to notice.