US Government Monitoring Public Internet in Real Time

Here's a demonstration of the US government's capabilities to monitor the public Internet. Former CIA and NSA Director Michael Hayden was on the Acela train between New York and Washington DC, taking press interviews on the phone. Someone nearby overheard the conversation, and started tweeting about it. Within 15 or so minutes, someone somewhere noticed the tweets, and informed someone who knew Hayden. That person called Hayden on his cell phone and, presumably, told him to shut up.
Nothing covert here; the tweets were public. But still, wow.