http://www.techcrunch.com/
I believe that Twitter (and Yammer but probably to a lesser degree because it does not have the same "network effect") will likely emerge as part of an emergency management notification system.
Why? Because cell phones are now ubiquitous and provide real time publishing as events are unfolding. We almost always have one available.
But there are probably other business applications in selected niches where this kind of real time communication is important. Perhaps competitive advantage going forward goes to those organizations that "communicate better than the competition."
Do those that communicate better learn faster?
We had the computer age. This was followed by the information age. Now we are living in the communications age.
Here's some more real time tweets from Mumbai.