British Government Hands Out Electricity-Monitoring Gadgets

Here's an idea for promoting energy conservation: British energy companies, at the behest of the government, are handing out free energy monitors to any household that wants them. The monitors have a control unit that hooks into the house's electrical meter and a display unit that customers can use to test the electrical usage of any gadget or appliance. The article on the subject on TimesOnline doesn't state how the monitor works, but I imagine a plug is involved. Makes me wonder what that gadget would tell me about my energy usage…
I guess that means I'd have to move, then.