there is an actual way to add foot prints to people which remain for others to track for a certain period of time, but it is heavily resource intensive. Very, very interesting though, as it takes into account trackless step and such, but, for the majority, it leaves long lines of tracks for set period of time every where they go.
If the server were being run on a super computer i could see it implamented, but, as far as general realistic tracking, it might be hard to make something widget wise. I'm sure the dev team will come up with something if the idea is accepted though, nod, nod.