Earlier quoted context omitted.
I know of a case where a baby died of asphyxiation while sleeping on the parent's bed. It may be isolated incident or whatever but I wouldn't dismiss this risk.
There are other cultures where sleeping with your baby is the norm, and they don't have issues babies dying left and right due to parents rolling over on them, so I think we need more than anecdotes to say that it's dangerous.
"There has been a fourfold increase in the rate of infant strangulation and suffocation in the U.S. in the past 20 years, according to a report released today, and the apparent cause (though hardly the definitive one) is the rise in numbers of babies who share beds with their parents." source: http://parenting.blogs.nytimes.com/2009/01/26/the-risks-of-s...
"The American Academy of Pediatrics (AAP) and the U.S. Consumer Product Safety Commission (CPSC) warn that infants should not co-sleep with their parents." source: http://www.marchofdimes.com/pnhec/298_29656.asp
"Adults sleeping with babies increases risk of sudden and unexplained infant death, inquest finds" source http://www.theaustralian.com.au/news/health-science/adults-s...