Weather MappingOkay so this is one of the things I think will be very cool to watch evolve as more people start to realize and utilize the power of the wonderful mapping systems Google has bestowed onto us.
Meet Google Weather Maps (http://www.weatherstationmaps.info) which uses interesting icons to show temperature and wind direction as well as sunny/rainy/cloudy icons. This view can be exported to Google Earth by clicking "Export current view" to the right of the map, or for radar maps in Google Earth, just select a state click "show".
Now you have a radar map (with transparency) which can be edited to update automatically by right-clicking each overlay (in the my places pane) and selecting "edit". Also you can right-click the overlay and select refresh to manually update. Don't forget the transparency slider for your image, which appears when you select an overlay. I believe this is the evolutionary beginning of the integration of real-time weather satellite/radar imagery maps and Google Earth.
I also found this collection of satellite image overlays (hint: click "download this file" in the center of the page) on GoogleEarthHacks.com. Its a collection of WeatherChannel satellite images imported into Google Earth and overlayed and they should automatically update every hour. The update frequency can be edited as mentioned above. (note the picture 2 posts down under GoogleEarthHacks.com shows one of these overlays in action)