My Tracks Android application for T-Mobile G1 and other Android-powered phones, lets you records tracks of outdoor activities using the phone's built-in GPS. It shows these tracks on a map and presents live statistics, including an elevation profile. It also lets you share your activities with friends and the world using Google Maps, as well as archive your training history with Google Docs. By default this is the Gmail application, but if you have installed other applications that can send messages, there will be more options, explain Google LatLong Blog.
To download My Tracks to your G1, go to Android Market and search for “My Tracks” website.
More info: Google Blog