I want to toggle between map view and satellite imagery in Google Earth like I can in Google Maps.
Is there an easy way to add Map View to 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)
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: