The G1 offers a lot of location based services including the ability to see where your friends are. Similar to Buddy Beacon the G1 can help you locate others as well as broadcast your location, however it is not limited to those who are using a specific application. It is the same with all Android phones.
The G1 includes GPS and AGPS. It does not currently support walking directions, but that feature is "very forthcoming". Google has redefined navigation on handsets with the drag and drop directions feature as well as Street View. Being able to see an unfamiliar location before you get there is a dramatic improvement on the way we use our phones to navigate the streets. Street View also allows you to look down the street, move down the street and also zoom in and out with amazing clarity.
Perhaps the most amazing feature of Street View if the compass feature that allows you to look around the street view in full 360 degrees by simply turning your body. This is truly something that one must experience for themselves to fully get the realization of how advanced this is. It is almost like looking through a spyglass.