This is the coolest thing I've seen all week, mainly because it works so well at this early stage.
There are tons of opportunities, especially local … Think about how easy it will be to find a cinema, restaurant, pub, petrol station, or bank. Or, if you mash it up with a social network, you’d be able to geo-locate your friends on a map. As someone said, “Then, you could poke them for real!”
The latest version of Google Maps for mobile phones has a new feature called "my location". Instead of having to enter your location, Google Maps is able to find it. If your phone has GPS support the location detection should be very good, but even if there's no GPS, Google Maps can approximate your location. "The My Location feature takes information broadcast from mobile towers near you to approximate your current location on the map - it's not GPS, but it comes pretty close (approximately 1000m close, on average)." To find your location on the map, just press 0 and look for a blue dot.
To get the new version (2.0), go to http://google.com/gmm on your mobile device. Despite being in beta, I thought it works very well.