In case you are not familiar; a Twitter hashtag discussion is where any number of people across Twitter converse on a topic.You simply add whatever the hashtag being used to your post and set up a search for that hashtag to view all the relevant posts by the people joining in.
On Thursdays from 9-10 EST there is an ongoing chat for role playing games (pen and paper Dungeons and Dragons style).
I am going to start archiving the discussions for posterity, with Tweetdoc generating a .pdf every Friday or as soon after as I can.
On 3-31-2011 the discussion topic was player buy-in, or getting players to feel really part of an on going campaign world. The archive at tweetdoc is here (go to the bottom of the page and scroll up to see the convo as it happened.