I'd like to add that I think opt-in versus opt-out is only part of the picture. (I am agreeing with many of the points made above and just spelling things out as I see them -- a little more detail at http://technosociology.org/?p=102). What we are witnessing is a tragedy-of-commons for privacy and surveillance. Four points: 1- Our social commons have moved online; it does not make sense to tell people to avoid these services as they essential to participating fully in the life of the 21st century. 2- Many of these are natural monopolies; due to network externalities, it makes sense that there will be one big online auction space (Ebay), one big search engine (Google), one big social directory (Facebook), one big encyclopedia (Wikipedia), etc. 3- These are corporate-controlled environments where it makes sense for those who control the design to maximize visibility. Design online is what space is to offline; it shapes and structures behavior. 4- Most people most of the time will go with the flow. Availability of opt-out will let those for whom this is a problem at the individual level to avoid negative consequences but that does not get around the societal level consequence. And that consequence is micro-level behavior that is searchable, permanent and public. That is the world we are slowly but surely creeping into. -z ----- Zeynep Tufekci, Ph.D. Department of Sociology and Anthropology University of Maryland, Baltimore County zeynep at umbc.edu or @techsoc http://userpages.umbc.edu/~zeynep/ http://www.technosociology.org