For my final university thesis I analysed 2500 tweets from Finnish members of parliament during 2009-2010 to see how they communicate with each other and people in the public sphere. Here’s the final thesis in Swedish (PDF alert).
I made no great discoveries partly due to Twitter being quite a new means of communicating but I did create a precedent for anyone wishing to make a followup to it. One thing I did find was that many used Twitter as a way to show that they were actually doing something for the people that elected them. The tweets were evenly divided between professional and personal updates but some focused on personal things while other only had professional tweets.