On maps.google.com you can see a brilliant example on how a google maps application can suddenly turn into a google earth application smoothly.
I\'m developing a goo
To add the Google Earth instance to your map, simply add the G_SATELLITE_3D_MAP to your map with GMap2.addMapType().
var map = new GMap2(document.getElementById("map_canvas"),{ size: new GSize(640,480) } );
map.setCenter(new GLatLng(42.366662,-71.106262), 11);
// Enable the Earth map type
map.addMapType(G_SATELLITE_3D_MAP);
var mapControl = new GMapTypeControl();
map.addControl(mapControl);
map.setMapType(G_SATELLITE_3D_MAP);
Here is the information on Integrating v2 of the maps Api with the Google Earth Plugin http://code.google.com/apis/maps/documentation/javascript/v2/services.html#Earth