As an occupational therapist who works with infants and toddlers, I have seen first hand how great infant massage can be! This article highlights this:
Infant massage: Understand this soothing therapy - MayoClinic.com
Seven years ago, I went through training to become a certified infant touch & massage instructor (CITMI). I did this so that I could teach parents of my clients how to massage their babies. Sometimes when a child has multiple disabilities and medical problems, there is minimal things that a parent can do to truly bond with their baby. When you teach those parents how to massage their infant and how to read the signs of their baby (respiration, state of arousal, emotion, etc), all of a sudden the parent seems to feel more competent as a parent that they could provide a source of enjoyment for this baby who has so many medical needs. Also, for some children it shows that touch doesn't have to mean pain. Medically fragile infants have been poked with needles and tubes so much that they may become aversive to touch if not exposed to a pleasurable touch as well.
For babies with development delays massage can be beneficial too. The massage can loosen tight muscles as well as stimulate floppy muscles. The massage can aid in "body in space" awareness which can then lead to the child achieving motor milestones such as rolling over to the tummy and back.
Massage can be just as important for typically developing infants, especially if they tend to have constipation or reflux. When I was going through the training, my daughter was 2 years old; she really enjoyed me practicing the various massage strokes on her arms, legs, and tummy. She would even come ly on my lap and say "saj me mama"... a great measure of bonding and success!