How to create a Google Map with SVG vector overlay

There is a Download SVG with Google Map button on MapSVG start screen. What does it do? If you want to overlay an interactive vector graphics on top of Google Map, you should download a calibrated SVG file with Google Maps screenshot, edit the SVG file in Inkscape and then upload the file back to MapSVG. Your vector graphics will be automatically overlayed on Google Map by MapSVG.