Just for shits and giggles yesterday, I popped into Radio Shack and bought a police scanner. While I was working yesterday, I plugged in some earphones and listened to three frequencies that the NYPD uses for crowd control. It was total chaos for a while, with lots of chatter and activity about protestors, re-routing traffic and all sorts of other stuff.
Last night, I took the 12:37 AM train from Penn Station to Ronkonkoma after W's speech. Even as the train cruised out to Long Island, I could hear the cops back in the city coordinating the removal and placement of barricades and allocating personnel to different areas to keep crowds under control. One thing I noticed was that cops tended to ask one another to call them on their cell phones if they had to discuss things in detail, so the fact that I didn't hear much about the processing of protestors who had been arrested was probably due to cops having private conversations with their wireless phones.
Just after 1 AM, the dispatcher broadcast a pre-recorded message from the police commissioner congratulating officers on a job well done. Afterward, the dispatcher had to shout down several officers for making "inappropriate transmissions" on the channels as they hooted and hollered.
All for $99 at Radio Shack, although I bet you could get scanners cheaper online...