I was contemplating today the idea of using twitter as a role playing environment for education. In this scenario, which I'm sure others have talked about (but right now I'm too lazy to search for), you would assign students take on say, historical or fictional figures in twitter, based around some event such as Watergate or the Battle of Waterloo or Shakespeare. Each student would then be responsible for researching the time line for that event and how their assigned persona fits into it. They would then each tweet imaginatively about their view of that event as it unfolds around them; as how they imagine that person might view things.
An example of this, although based around a fictional television-based world, are those who tweet as various Buffy the Vampire Slayer characters.
I have no idea if such an exercise would work, but I'm intrigued by the possibility.