Google announced today that Google Maps Navigation (Beta) is now available on devices running Android 1.6 (Donut) and higher, such as the T-Mobile myTouch 3G and the G1.
Google Maps Navigation comes with everything you'd expect to find in a GPS navigation system, like 3D views, turn-by-turn guidance and automatic rerouting. If you have a phone running Android 1.6, you can download an updated version of Google Maps from the Android Market to use Navigation today.
One feature not available in the Android 1.6 version is the "navigate to" voice command. However a new 'Layers' feature is available. Layers lets you overlay information on the map., such as My Maps, transit lines and Wikipedia articles.
Via: Official Google Mobile Blog