The doctor/midwife simply does a finger/hand "sweep" of the membranes to remove them from the lower uterine segment. This action can cause the body to release prostaglandins, which can initiate labor contractions, much the same way cervical ripening does. However, this is usually only done when a cervix is "ripe" and ready for labor, in the first place.
It can be quite uncomfortable and crampy and like many things to attempt to initiate labor, it either works, or it does not. It is as unpredictible as that.
Implications are the mom either goes into labor or not. Also, in the action of stripping the membranes, the practioner may actually rupture them in the office, therefore making it necessary if the mom is planning to have the baby in a hospital , to go to the hospital right away, for active labor/and/or induction of labor.
It's a very "low tech" intervention, when compared to labor induction using hormones such as prostaglandins/prostin gel, cytotec, cervidil or pitocin drips.
Another way to initiate labor is via nipple stimulation---this action causes the pituitary to release oxytocin (the natural form of "pitocin") and CAN cause spontaneous labor.
OF course, another way to bring on labor possibly, would be having sexual intercourse, as semen contains prostaglandins in it, and can therefore, act chemically on the cervix to ripen it, or to cause labor contractions.
There is no surefire way, clearly, to start labor. When and if somebody figures that all out, he/she will be one rich person!