Calculate geographical coordinates for equidistant points at vertices of a triangular grid

I needed to set up a grid of equally spaced insect pheromone traps. While it is convenient to put traps at the vertices of a rectangular grid, this is not optimal because nearest neighbors on the diagonals are further away than those within rows or columns (If the spacing within rows and columns is X, then the diagonal spacing is sqrt(2)*X). For equidistant spacing, points are placed at vertices of a grid made with equilateral triangles. This python script calculates such a grid of points and returns the data as a KML file containing latitude/longitude coordinates in decimal degrees.

The KML file may be displayed using Google Earth.