There is an account that the flight was met in Miami by police and TSA staff, and that the captain declared that the purser was a terrorist.
Flying the IGS for Pan Am out of TXL we were taught the difference between a German purser and a terrorist - you can negotiate with a terrorist.
Here's the track and flight plan of the divert:
FlightAware > Live Flight Tracker > United Air Lines Inc. #842 > 13-Jul-2009 > SBGR-KMIA
I do wonder why they would go to MIA instead of MCO, especially since the original route was over ORL. MCO has pretty much the same tactical assets as MIA from my experience, I've been based at both places over the years. Of course, at that time of night, you usually get directs in U.S. airspace anyway so routing was probably not an issue.