Twitter as a Mood Ring

I stumbled across (what I thought) was a novel, fascinating study that mapped the country's moods throughout the day -- using word analysis of Tweets.

Pulse of the Nation: U.S. Mood Throughout the Day Inferred from Twitter

According to the maps, the District and environs spend most of the 24-hour cycle feeling rather stressed, angry and generally unhappy, whereas life in the sunny states like Florida and California appears pretty relaxed and even-keeled.

Vacation ideas forming, anybody? :)