The idea behind the heart is that connected to arduino you can make it vibrate. So when I squeeze it, someone who has the other heart would feel it vibrate or it would vibrate according to my squeezes. This way that person far away would know you are thinking about her/him.
Also its very aerodynamic. You can use it as a boomerang or ninja stars to represent a heart “attack” but it doesnt hurt. So you can poke someone with it just to make a joke!