I think it is nothing special, except the geometrical design of the shape. Technically, you can't really arrange three triangles to form a bigger one. So, what they did was to make a single pattern of Sierpinski's Triangle, where you connect the midpoints of the sides of the triangle to form four triangles, where the one in the middle is upside down. Therefore, I believe there really isn't anything special; it is just a geometric design after all.