Waypoints from Google Maps

Just seen the following tip in a review for a portable GPS device.  


You can use google maps to get waypoints to store in your gps which can then be used to plan a route. All you have to do is go onto google maps and double click on a location to centre the location and then by typing the following code into the address bar in the browser you can retrieve the coords:

javascript:void(prompt('',gApplication.getMap().getCenter()));