Google began offering more ways to get data into and out of Google Map Maker. With the latest new features, Google now allows users to bring data into Google Map Maker using “Overlays”. Allowing users to overlay kml and image files on top of the map tiles to assist with mapping. You can test this feature with Panoramio kml file, adding this kml will drape user-contributed photos on top of your map to give you a ground view no matter where in the world you are mapping.
More info: Overlay Tutorial