Open Source means that you never have to wait for any company to release software in a rigid fashion. We are talking about the Nokia N900 and the Maemo platform.
There is no Google Maps for Maemo so far and we are doubtful if Google will even make one as they are concentrating on Android. So here is a Browser based Google maps application for Maemo which has come from the Maemo Community. Its got almost everything even Google Latitude