"Information about you will follow you around online. This will let you maintain your persona and reputation as you move about the virtual world. However, it raises concerns about privacy. Who will control this information? If individually controlled, the system is unreliable - I'm unlikely to share unflattering data about myself. Yet an externally controlled persona raises the disturbing vision of a society under ubiquitous surveillance."
Judith Donath, assistant professor at MIT Media Lab and director of the Sociable Media Group