I have heard that before but I don't see how it would work, nothing on an outside "smart" meter could affect only your central heat, short of cutting all power to your residence. Now if there is a special thermostat they want to install that would an entirely different issue (and easy enough to circumvent as you can override the thermostat entirely by fiddling with a couple wires in your furnace - I had a bad thermostat once and being too cheap to replace it I wired up a simple $2 Radioshack on/off toggle switch). Not to mention you could always easily circumvent any power company meddling just by purchasing a couple plug in space heaters.
The more sophisticated Smart Meters have a second wireless system designed to be used to communicate with “smart” devices in your house, like the thermostat (or the gov’t microphones).
Except that eventually, the smart meters will interface with smart appliances so not only will your minute by minute usage be tracked, those that care to will know exactly what your usage is for...