This is very cool. Roman Nurik of the Google Maps team has created a driving directions simulator for the Google Earth plug-in. With Roman's tool it is possible to enter your requested directions into the Google Earth browser plug-in and watch a car simulate driving the route. Check out the screen capture below.
My first thoughts on this are that you could use this to create virtual tours of any area on Earth or that you could add street view to this as well so that you could have a first-person view of the route.
Via: Google Geo Developers Blog