There is a good bit of misinformation out there about "cosleeping" - a mother sleeping with or very close to the infant. With the proper setup, this is a very healthy, natural sleeping arrangement for the child. In fact, it's very hard to argue against such an arrangement, as this is what was done for millions of years throughout evolution: the infant sleeping on a mat next to the mother.
All sorts of good things happen when a mother and child sleep close. Here is a good research paper(pdf) on the topic that provides more detail. It is my opinion that cosleeping should be the "default" sleeping arrangement recommended by pediatricians.
