The name Valentine may have come from this story.During the reign of Claudius 11 Valentine went against the Emperor and secretly performed wedding ceremonies. He was put to death on February 14th.
I also wondered why a heart is heart shaped. The most interesting story that I found was that the seeds of the now extinct silphium plant had heart shaped seeds. The plant was widely used in ancient times as a herbal contraceptive. The design is used in many european folk art such as n traditional narrow boats rudders and sliding cabin hatches, Farm carts, playing cards, Welsh love spoons, tattoos...the list is endless. Funnily enough it's not a design that's used on Gypsy wagons, at least I've not seen any. If you take a look at http://googlesightseeing.com/2005/08/heart-shaped-things/ you will find aerial photographs of heart shaped things.
The picture on the left is a set of money box stools that I painted in canal style. The other is a hole in some corrugated sheeting that I saw while out on a walk.