Look closely at the image of the iPhone--see the app with the letter H icon? That is a mock up of an iPhone app that would use the GPS system in the iPhone to help users to find historic sites when they travel. It is the brainchild of Twitterer DriveByHistory, known to you squares as Cynthia Sengel. Click here to play with the mockup and see how it would work.
I blogged a while back about the Duke Digital Collections iPhone app. But what is really promising about mobile devices is the promise of making history, well, mobile. Imagine being a road trip where you were alerted not just to historical markers but to museums that are currently open, historic trails along the way, old cemeteries, buildings on the National Register, etc., in each case with some pictures and a quick text blurb to tell you more. My immediate thoughts are 1) that would be amazing, and 2) I'd never get anywhere.
The next step would be to develop location-specific content for such mobile devices. How about a geotagged podcast that would take you on a walking tour of a historic site without having to have a set route? Or a virtual museum guide who knew what room you were in and which painting you were looking at? Or being able to see your location on a historic Sanborn or other map, or compare historic photos to the present-day house or building in front of you.
There was recently an interesting post over at Wired about a "Bionic Eye" iPhone app that produced "augmented reality." It looked to me like a good way to get hit by a car. But these augmented reality apps that overlay data from the internet on the scene in front of you have obvious uses for creating historical tours. In a few years you will see people standing at the edge of the Gettysburg Battlefield and holding their smart phones in front of their faces to see Pickett's charge reenacted on a 3" screen.
Also, it would be nice to see a way for historians to develop mobile content in a platform neutral way. I cannot see having my public history students develop content for a proprietary device that they cannot themselves afford.