Yes, but you'd have to download the maps while you're still on WiFi so that the tablet will know what those GPS coordinates 'mean' when you don't have a network connection.
If you want real time turn-by-turn navigation, however, it's a different story and depends solely on the app you're using. Google Maps, for instance, lets you download map areas (as long as the city or country has not restricted it) but it won't give you turn-by-turn directions or let you search for specific addresses while offline. Some more dedicated apps, like the ones bclinger suggested, do let you download maps and have Navigation even when offline, but of course, you'll need to download the relevant data before you go on the road.