The car is the ultimate "mobile device" isn't it? And increasingly cars are becoming "connected" to the Internet. Google now has an impressive roster of car brands on a global basis to which users can send Google Maps directions.
According to the Google LatLong blog:
With today’s additions, drivers can send destinations from Google Maps directly to their connected vehicles in 19 countries and more than 20 different brands.
In the US alone, Send-To-Car is now available on more than 15 car brands and we hope to see even more partners join us soon.
On a smaller scale Mapquest and Nokia's Ovi Maps offer in-car integration. However Navteq (owned by Nokia) powers most of the PND devices that operate in vehicles in the US. In Europe it's Teleatlas, owned by TomTom.