Privacy is the new poverty. This struck home for me when doing the last.fm mashups for the Roskilde Festival and the Jazz Festival. They work better if you've given up your privacy and told last.fm about you for context. And not in a shallow way. The more you tell, the better it works. You can decide to start today, to make up a persona for the musical you, but it's not going to be you in the rich way that 2-3 years of listening will.
Google Social Search is another case in point. The privacy bogeyman is taken out of the cupboard when presenting these things - it's almost a tech ritual - but the simple fact of it is: There's a lot of value in letting yourself be known on the internet. There are services you simply cannot buy with money; you can only buy them by investing yourself.
Philosophers, social thinkers, existentialists and anthropologists are all going to have a field day with this. If I put up an appearance - act out a character essentially different from the real me - on Last.fm, I am simply not going to get the value of deeply meaningful musical recommendations. You might consider music frivolous, but your politics, the writers you read, the economic decisions you make, are much the same.
A lot of the characteristics of the city - the big frictionless, anonymous market place of cultural exchange - that we've grown accustomed to, and from which a lot of our notions of freedom spring, become meaningless in this future world. In a cultural context, the sanctity of the home is the right to secrets. To your own thoughts, whatever they may be. And of course we will uphold that right; but keeping them private is going to make you poor. Freedom is expensive.