With the spread of social media and cloud applications, this debate has a new fervour. Google repurposing personal data for its Buzz venture and sniffing wi-fi, limits on Facebook users' control of privacy settings -- every incident of this kind brings enough howls of protest to persuade us that people still value their privacy.

On the other hand, it is often said the new generation think differently and are keener on sharing information than keeping it private.

Some people have simply given up the struggle to stop their information getting everywhere.

Privacy is dead, we are told. I might feel inclined to believe it, were it not for the impression that the loudest voices in support are the very marketers and pollsters who stand to gain from that attitude. I suspect a little social engineering.

Another view, which I find more persuasive, is that when we make use of a service like Facebook, we enter a commercial bargain. Something very useful is provided to us free of charge and in exchange we cede something of our private selves to the providers, to be sold for whatever they can earn.