It's like walking into a crowded room of people who are having a hyper-lively conversation about one topic, and then being able to overhear all the bits of it, clearly. In this case, the chatter, after a short while, suggests how Obama and McCain are "playing in Peoria" (or anywhere else, for that matter). Consider it a kind of crowdsourced, informal focus group —a good example of how Twitter can convey a kind of "first-read" of public opinion. Mesmerizing.
(Illustration: Communicating by Miroslaw Pieprzyk for istock.com)