Charlie Fitzpatrick of the ESRI Education Team, recently posted a great blog on, as you might guess, collecting location data with the iPhone and displaying it in ArcGIS Explorer.
"Like most iPhone users, I delight in picking up "new" uses for it. When away from home, I use my phone's built-in GPS to track my morning run and get me back safely. Last week, I rode the train from DC to Philadelphia to exhibit at a conference for science teachers. As I sat down on the train, I decided to follow our progress."
Read more at the ESRI Education Community Blog