A useful thing?
Well, not wanting to detract from all the witty comments above but is it the case of right technology, wrong application?
Rather than trying to get a report of the effectiveness of the baby's sleep - which I'm sure is self-evident to any parent - isn't it better to use the technology in conjunction with push alerts to combat real problems like cot death? If these sensors can be used to monitor the baby and alert the parent to events such as stopping breathing, a slowing of the breathing (since the earlier something wrong is noticed, the better), etc. then that's how it should be getting used.
It seems to me that this would be a far better way of using sensors attached to a baby than to be alerted to it pooing.
Biting the hand that feeds IT
