TeleNav are set to offer the first GPS navigation service for the G1 at the end of February. At first, it will only be available via the TeleNav website, but it will soon be available from the Android Market. Right now, TeleNav are offering a 30-day free unlimited use trial of the service. Once your time is up, you will be able to retain the complete service for $10/month.
The software itself offers colourful 3D maps coupled with both voice and on-screen turn-by-turn directions. Depending on your screen size, you may wish to view the application in portrait or landscape modes, so naturally the application supports both. There is location-based weather data and even automatic rerouting should you decide to deviate from the current path. Combine this with gas price listings, traffic alerts, and speech recognition for single button press address entry and we’re onto a winner!
However, the cherry on top and my favourite aspect has to be the online preplanning available through the TeleNav site. This makes getting started on your trip that little bit quicker should you have been sat by a computer (e.g. in the office) before you get into your vehicle.
There is an excellent review of this software available from the blogs of ZDNet. Android Community also have a review and both sites offer a YouTube video and image gallery.