If you have smart phones (Android or Apple), take a look a look at ViewRanger combined with SocialHiking.
Using ViewRanger and enabling BuddyBeacons within the app, then linking via Twitter to SocialHiking you can get a near realtime view of the location. For an example check the SocialHiking webpage for maps marked Live.
NB - this does rely on some form of data signal, although it doesn't have to be full 3G. This could be an issue in some remote locations.
One thing to note is that it's a good idea to keep an eye on battery consumption and either have spare batteries (Android) or a means of recharging the battery in an Apple.