Runners enter their unique Run ID (as of now, any number from 0 - 10,000) and carry the phone during marathons or other running events. This Run ID can be privately/publicly shared with their F&F.
Family and friends of runners can then view the runner's location and stats like distance covered, pace calculated every mile along with average pace and expected finish time. The location of the runner is provided on the custom map (route, mile markers, water stations, toilets, entertainment area) and with the integration of G-Streetview images, viewers get a feel for the runner's perspective of the location 'in real-time'.
Details here: http://www.odikyo.com/about/
While this app was designed for runners, it can be used by cyclists, walkers, hikers, joggers alike.
Odikyo means 'to run' in Malayalam (South Indian language).