Google is expanding the availability of Google Maps Navigation to devices running Android 1.6 (Donut) and higher such as the T-Mobile myTouch 3G and the G1.
This follows the recent launch of Google Maps Navigation (Beta) as a free feature of Google Maps on Android 2.0 devices.
This release also includes the new Layers feature, which lets uses overlay geographical information on the map.
Some features of Android 2.0 are not available on Android 1.6, like the ability to use the "navigate to" voice command.