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Using Facebook Lexicon, a tool that looks for occurrences of words and phrases on Walls over time and displays them on a graph, they've released a couple of screenshots which show how the discussion of the swine flu on Facebook went over time, and how it spread geographically.
Unfortunately, the current version of Lexicon doesn't support geo data, and the new, beta Lexicon only lets you choose from a number of predefined phrases, so I wasn't able to play with the data myself, and Facebook didn't give us too much data. Still, the maps, which show the percentage of people in the US, UK and Canada discussing swine flu on their wall posts in the previous week, are worth a look; see them all here.
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