Within the various ways I think Twitter can be applied, I do not include serious discussion. The 140 character limit is simply not suited to formal discussion and the common practice of using the tool for group chats seems to me to focus on quips and quotes with little evidence of personal explanation or exploration (I kind of like this sentence.).
It appears Twitter is considering ways to offer users the opportunity to say more. Twitter would remain a micro-blogging platform, but the opportunity to express yourself in greater depth would offer users to have more effective conversations synchronously.