Statistical wording analysis of political speeches

There's been some interesting work lately in analyzing documents and speeches in terms of statistics and word clouds and such. The most recent piece I've come across in this area is Janet Harris's Huffington Post article “From Reagan to Romney: How Last Night's Speech Measured Up,” written shortly after Romney's acceptance speech at the Republican National Convention. It examines Republican nomination acceptance speeches over the past 32 years, looking at things like wordcounts and word clouds for each speech.