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The researchers said German firm Discovergy apparently allowed information gathered by its smart meters to travel over an insecure link to its servers. The information – which could be intercepted – apparently could be interpreted to reveal not only whether or not users happened to be at home and consuming electricity at the time but even what film they were watching, based on the fingerprint of power usage.
http://www.theregister.co.uk/2012/01/09/smart_meter_privacy_oops/