“Anything that is useful to both dissidents in Iran and Martha Stewart has a lot going for it; Twitter has more raw capability for users than anything since e-mail,” said Clay Shirky, who wrote “Here Comes Everybody,” a book about social media. “It will be hard to wait out Twitter because it is lightweight, endlessly useful and gets better as more people use it. Brands are using it, institutions are using it, and it is becoming a place where a lot of important conversations are being held.”
Twitter helps define what is important by what Mr. Shirky has called “algorithmic authority,” meaning that if all kinds of people are pointing at the same thing at the same instant, it must be a pretty big deal.
—Why Twitter Will Endure
(emphasis mine)