I don't think it's a boy/girl indicator but for me...it was a good indicator of their personalities as they grew.
DD wasn't overly active in the womb. She had her active periods but I knew her schedule based on her movements. She was quiet all night and then had her morning and afternoon spurts and then was quiet again. She was like that as a newborn and was the most easy going baby.
DS was VERY active in the womb. All day. To this day, he doesn't sit still!!! Always a very active baby!!