Wow! Mercedes has just introduced this new feature to a few select 2008 models. The S, CL and Tele-Aid equipped C-Classes can now receive directions downloaded from Yahoo or Google Maps. You can visit the official site here to watch the video and get all the details. It really is simple and very cool.
I think the best part is that it allows you to customize your route online to the way you want to travel and then download that particular route to the vehicle. For example, navigation always wants me to go through St. Louis when I travel from Champaign, Illinois to Georgia, but Google allows me to choose a more direct route. Then I can download those directions rather than listening to navigation requesting a U-turn for 20 miles! Another great way to use this system would to have your secretary or assistant send directions to your car while your out doing business. Let me know if you try it!