Like a balding hipster who imitates a young trendsetter’s style, Facebook is updating itself to look a lot more like Twitter.Unlike Facebook, where friends mutually agree to let one another into their online lives, Twitter lets people share updates and links with anyone who cares to read them.That has turned Twitter into a tool for people to peer into the collective mind and see what people are talking about in real time. It is also a tool for businesses to reach customers and monitor what their customers are saying about them.
http://www.nytimes.com/2009/09/14/technology/internet/14facebook.html