They were beta-testing a new athlete tracker technology.
As Lagat rounded the track at the Reggie Lewis Track and Athletic Center in Roxbury, running the 5000 meters in thirteen minutes and eleven seconds, the tag relayed information about his precise position on the track to a Lynx computer system in a control room above the action, which enabled a robotic camera to closely follow Lagat, and provided detailed new information for the ESPN announcers who were calling the race.The linked article talks about using the tracking "to give announcers information about estimated finish times, for instance, or can be replayed afterward by a coach to help runners identify the points in a race where they may have slowed down".
I think they're totally missing the best possible application for the technology. Ever see the name/data pointers they use to identify cars on NASCAR broadcasts? We now can do the same for runners during televised meets. Never, ever stop thinking about how to make a sport better on TV. The competitors aren't.