Augmented Reality & GPS Visitor Guide Apps are cousins coming from the same roots. Using location determined by numerous technologies (GPS, WiFi, Bar Codes, Image Matching, accelerometer for Direction, Bluetooth, etc.) to determine what to display that is relevant. Relevant could be 
stories, facts, predictions, news, etc. relevant to the space you are moving through. The space could be hiking up Half Dome, inside a museum, or walking down the street to Starbucks. What makes augmented reality different is that the display uses the camera as the background and then overlays information on top. Layar is one of the early moves in this augmented Reality space. Today’s iPhone Apps Guides for Yosemite Falls, Zion, Acadia, and the Great Smoky Mountains are very similar to Augmented Reality.
National Geographic has great vision / prediction about the future of Apps / how visitors will get information as they move through spaces. For Cooperative Associations and National Parks if you dipping your toe into Apps / Visitor Guides remember that you need to be flexible as platforms for your content evolve. If 10M people are using Layar or Every Trail you should assume that you want to offer your content inside multiple Apps and on multiple platforms (iPad, iPhone, Kindle, etc.)
