I was thinking this same thing this morning as I tried to figure out where I needed to go once I got off the subway using the new google maps. This is a neat idea, but I wouldn't use it until I feel confident in the GPS and compass in my phone being accurate. Right now it's only right about 50-75% of the time (an one fo the times when it is notoriously bad is when it is finding its bearings after being without servie underground.)