Well, it's obvious why DARPA would care how quickly the internet can become aware of accurate and specific information such as 'where is unit X'.
What I'm curious about is how much mis-information could pop up. What if you mischievously set up your own balloon, that looks identical to the description, as a distraction to other teams/groups?
What if groups eventually find all the balloons - and there are 13 of them? Is it then time to unleash the perl scripts on DARPA's submission form? So many possible strategies and counter-strategies - but are they actually all just intellectual, or will they play a role in the challenge?