People are all panicky about smart meters, and they imagine they're some kind of Big Brother device that reports on their TV watching habits, or know exactly what kinds of subversive web sites they visit based on their power usage, and report their pr0n habits to the gubbamint. But "smart meters" are not "omniscient meters". They just measure your home's overall consumption of electricity, same as your current meter.
Smart meters essentially work like what you're talking about. The difference is they are in near constant communication with the utility, so they broadcast a rate schedule to your home's appliances that advertise the current and near future electric rates, and they can report overall house consumption on a near-real-time basis. And that's about it.
The utility can predict "At 4:00 today it will be very hot, so we will be bringing on supplemental generators at that time to meet all the extra A/C demand." They also know that regular electricity normally goes for $0.08/kWh, but supplemental generators cost them $3.00/kWh. They then tell the meters the rate schedule for today is $0.50/kWh from 12:00 to 3:00; $0.60/kWh for the first 2kW from 3:01 to 8:00, but $5.00/kWh for everything above 2kW; and $0.20/kWh from 8:01 to 12:00. The meter then announces the price schedule to your home appliances. You may choose to have your washing machine configured to run only if the cost of your electricity is less than $0.25/kWh; you may have your thermostat set to reduce air conditioner use when the cost is greater than $0.75/kWh; and you may set your electric water heater and pool pump to switch completely off if the cost is greater than $1.00/kWh. It's all your choice, how you want to manage your consumption remains up to you. You simply have to know you'll pay more when overall demand is greater.
Your electricity usage today is not a secret. Your meter already reports usage to your utility company so you can pay for what you use. But today, your dumb meter can't tell what time of day the electricity was consumed, and it doesn't know the rate in effect when you consume it, so your utility company has to front-load everyone's rates with the predicted cost of supplemental generation, the future cost of fuel, etc, and they only change the rate on a monthly or annual basis. What will change with smart meters is the rate you pay will depend on the rate in effect when you consume it; the meter will know the current rate and you will be charged accordingly. Even after smart meters roll out, how you choose to use the energy your house consumes is still up to you, and whether or not you're spending it on a dishwasher or indoor pot-growing farm is still not the utility company's business.