Turning on map view in Google Earth?

There is a Google AppSpot website that will let you overlay Google Maps (and many others) in Google Earth for Free (You do need have a gmail account and allow the site monitor your usage)

http://ge-map-overlays.appspot.com/

Google doesn't allow it. There are some folks in the Google Earth Forums that have found some "unofficial" workarounds: http://www.google.com/support/forum/p/earth/thread?tid=4a722cff2ea80a5c&hl=en. Complied from a few posts on those forums:

http://www.gelib.com/google-maps.htm

http://www.mgmaps.com/kml/

http://bernhard.sterzbach.de/googlemapsoverlay.html

http://ge-map-overlays.appspot.com/