Update: a real example of twitter entropy at work, after the 11 am ceremony the tweeting at the monument declined while tweeting rose in other area around it as people spread out.
Seeing very high levels of tweeting from the area around the ceremony for Remembrance Day in London. Below shows a bit further north. We are estimating a few hundred tweets an hour within 250 meter of the center of the ceremony, with much lower levels of tweeting just outside.
These levels of tweeting show how much the use of mobile phones and twitter has become a part major events in the western world.