Sounds like I'm a bit late, but I just caught onto the 'MadMen Twitter craze'. It immediately reminded me of Matt Beaumont's e, where a story is told through the emails of staff at an ad agency, but as you can read here, this story (t?) is inevitably more complex and interactive. Who are the 'real' characters? Who knows. Who cares.
I'm sure the same idea has been played out with other TV shows too(?) but I suppose it works especially well for a show that appeals to ad people that probably use twitter.
I love the idea of a story playing out across these kinds of tools. In fact, I started one myself a while ago but gave up quickly from a lack of time/motivation. My idea was to tell a serial killer's life through a blog, called Killer Blog.
I quickly became uneasy with the idea and decided to make it obviously jokey in case the Feds knocked at my door. Or whoever the dull, understated version of the Feds are in the UK.