It’s basically a ritual now: Fresh feature debuts on new Android phone; hack-happy HTC Dream owners see new feature, develop seething jealousy; said owners work tirelessly to steal new feature. Last week, Google Maps Navigation hit the Droid. Today, the G1.
AU: The G1 is called HTC Dream in Australia, but I wouldn’t bother trying this as Google Maps Navigation is only available in the US at the moment. -EH
Google Maps Navigation will be part of Android 2.0, and Android 2.0 is expected to come to most — if not all — Android handsets on the market eventually, so given how complicated this hack is (fairly!), and that it requires a rooted phone, it'd be prudent for most folks to just wait this out. That said, there's no saying on how long it'll be until Eclair seeds out to older handsets, and there's no guarantee that the G1 — an old fart in its little corner of the universe — will ever get it. Anyhow, here's what you need to do, from XDA:
Make sure you have CyanogenMod 220.127.116.11, by the way.
1) Unzip zip to desktop
2) Run Part 1.bat
3) When prompted to press any key, do so; the phone will reboot
4) When your phone is running again, run Part 2.bat
5) When prompted to press any key, the installation process is done.
6) Make sure GPS is enabled
7) Open Maps and press OK
8) Press Menu
9) Press Directions
10) Enter an end point
11) Click Go
12) Just under "Show on map", click Navigate.
13) When prompted to install the voice codec, do so.