Latitude works after a fashion, but is not without its quirks:
- The Symbian version is pretty much foolproof, updating at sensible intervals but will only use cellular positioning when the phone is in standby mode.
- The Android version stops updating after 15 minutes when the phone is in standby mode. Nasty hacks to inhibit standby work well (and will keep the GPS active, for accurate location), but leave the screen unlocked with the backlight on, leading to issues with random button presses and requiring vast amounts[1] of power.
- The Windows Mobile version is much the same, though it's been a long time since I attempted to use it, as my WM device had the worst battery life in the universe.
- I haven't used the IOS version, it used to be thwarted by lack of multitasking, but I think they've fixed that.
If you want reliable, a dedicated satellite-based device is the way to go. Anything cellular is going to fail as soon as you get out into the sticks.
If couple-of-hourly updates are acceptable, Latitude on a mobile device of choice that's allowed to go to sleep between manually invoked updates is a reasonable approach. I've been following andygates's progress on his E2E this way.
I'm sure smartphone-based alternatives to Latitude exist, but are going to have the same sort of power/accuracy/reliability issues.
[1] Realistically, you'd have to be running froma dynamo the whole time.
