As I've said before, I am not comfortable with cribs and dislike the ideas behind them (caging an infant in a time when their brains are developing and they need exploration and the ability to look around and take in their surroundings? no, thank you). Since we're leaning toward more Montessori ideals, introducing a Montessori floor bed just made sense.
A floor bed allows your infant to get in and out of bed under their own power, giving them autonomy. To quote from the Michael Olaf catalogue (a wonderful Montessori resource), "If we provide a floor bed or mattress on the floor in a completely safe room—rather than a crib or playpen with bars—the child has a clear view of the surroundings and freedom to explore."
Here is a little information from another Montessori mommy, not only on floor beds but on many other Montessori-infant-related things.
Currently, the BabyBeast's bed is in the same bedroom he's slept in since he came home from hospital: ours. It is about three feet away from our own bed, partly because that's how much room there is in there and partly because that distance makes it possible for me to get to him quickly if I'm dozing on the big bed while he's in his floor bed.