When I ran the Chicago Marathon in 2001 they used a similar system and the text messages said that you had passed the 10k point, etc., in so many minutes. They even had an automated system that rang your home phone every 10k and told relatives how you were doing. These were all actual running times.
I have run my last 3 London Marathons for the Anthony Nolan Trust and would also like to urge people to run for this worthwhile cause. I myself was diagnosed with Leukaemia 5 years ago and, touch wood, have beaten it to the extent where I have run 5 marathons and countless half marathons since then.