Demand response is very common indeed.

I used to work for a company that did load curtailment in anticipation of power demand peaks, because if you could lower (or eliminate) power usage during those peaks, the power producer would give you financial incentives. So we shut down our systems if we think the grid will peak.

And you're right about the little guys. If you give utility companies access to your NEST thermostat in exchange for a discount on power bills, they'll turn up your temperature on summer days automatically. (or you can do it manually).