Official Google Blog: Navigate and search the real-world … online or off
Finally! This will work great for those of us with tablets without cellular connectivity. You
Now you can download an area of the world to your phone, and the next time you find there’s no connectivity—whether it’s a country road or an underground parking garage—Google Maps will continue to work seamlessly. Whereas before you could simply view an area of the map offline, now you can get turn-by-turn driving directions, search for specific destinations, and find useful information about places, like hours of operation, contact information or ratings.