I use Google Maps all the time on my Android device, but with the online requirement for navigation I still have to reply on my Garmin GPS. Thankfully, Google finally announced that offline maps are coming in the next few weeks. You will be able to preload maps for other countries, up to 100 countries, and use the maps down to the finest level of detail.
Offline mapping is not just for foreign travel, but also great for other places away from cities where you may not have a data connection. Google had some basic offline support for cached routes, but it was nothing like having full offline access like they will be providing soon. My HTC One X just became a much more useful device.
In addition to offline maps, Google revealed some other upcoming features, including Street View Tracker, Map Maker expansion, and adding 3D models to Google Earth on mobile devices.