Starting with Hotspots 3 you are now able to show KML files on your map. But first for those that have no idea what a KML is let us look at the definition.
Keyhole Markup Language (KML) is an XML notation for expressing geographic annotation and visualization within Internet-based, two-dimensional maps and three-dimensional Earth browsers. KML was developed for use with Google Earth, which was originally named Keyhole Earth Viewer. It was created by Keyhole, Inc, which was acquired by Google in 2004. KML is an international standard of the Open Geospatial Consortium.
More information can be found on Wikipedia.