If you own an HTC Hero then look away now. Anyone with a phone that runs Android 1.6 and above can now download Google Maps (4.1.1 beta) with free turn-by-turn directions.
The update has been available in the US since last year - it turns your phone into a sat-nav and it's completely free to download. Engadget has tested it on an HTC Desire, Nexus One and Dell Mini 5 and we're told that it works in Street View mode, so you can see the actual street you're driving on instead of a map.
Google Maps Navigation will continue to run in the background so that you can hear directions even if you're browsing the Web - of course, we don't advise you to browse the Web while you're driving. To download Google Maps Navigation simply visit the Android Market and search for "Google Maps".