It's possible to show output of Yahoo pipes in Joomla. A Yahoo pipe can be output to a kml-file:

{mosmap kml[0]='http://pipes.yahoo.com/pipes/pipe.run?_id=BlagERoO3BGgl_e3X0sBXw&_render=kml'|kmlrenderer='geoxml'|kmlsidebar='left'|kmlfoldersopen='1'}

Thanks to Hani Juha.