I'm looking at this from the point of view of a normal electrical (or other utility) end user looking to save energy (saving money will of course depend on your rates, alternatives, usage level, etc)
What this whole discussion is missing is a number of simple, common sense design issues (solutions to many of which are already here). The smart grid is excessively complex, inelegant, and subject to all sorts of failures (including security issues). It is also in danger of leaving you in a place where if you have to revert to 'dumb' grid, you don't have enough capacity for the electrical end-users.
For some more elegant solutions that solve many parts of the same problem:
For air conditioning (and heating), we have a newer system (SEER 15) with a two-speed compressor and a variable speed air handler. This means that during the really hot and cold days where demand is up, the system behaves more like baseload (on a larger percentage of the time, but a lower power level) than peakload. More systems of this design would substantially smooth out the peaks. While there are no mandates, this system did get us a $1500 tax credit. (from Bush era legislation, no less). Also, a programmable thermostat really helps, particularly if it's smart enough to gradually bring temperatures up or down to your target (again, not having to run the system at full blast).
For refrigeration, at least in parts of Europe, vacuum bottle insulation is becoming quite standard for refrigerators and freezers. This is the same incredibly exotic, unusual technology that makes a Thermos keep your coffee/tea/soup hot for many hours without heat input. This saves a huge amount of energy via very simple efficiency, without any kind of smart grids or smart controls needed. Even better, give the refrigerator and freezer each their own compressor and 'try' not to run both at once unless you have to.
For lighting, there are already excellent solutions - CFLs, LEDs on the way, and motion sensors can automatically turn lights on and off if you want to go that route (not a bad way to go for something like hallways, though we haven't bothered). You don't need a smart grid for this, you just need a smart switch - localized means easier to implement, easier to fix, and no central control needed.
For water heating, the easiest and cheapest answer is efficiency. Wash your clothes in cold or warm water (they still get clean!), get a lower flow showerhead (The Delta H2OKinetic 1.6gpm ones are surprisingly nice, and this is from somebody who would drill out or remove the restrictor plates in the early low-flow designs), use a dishwasher instead of hand-washing dishes (uses much less hot water), etc. Insulated hot water pipes don't hurt either. But if you use a lot less hot water, it barely matters how you heat it. (though if you use electricity, the GE Hybrid coming out 4Q09 is worth watching - a heat pump water heater, with a normal resistive backup. Should be particularly nice and efficient if your water heater is in a warm place.) Besides, it's hard to beat the ROI of $30 or $40 for a new showerhead.
Finally, leaky electronics (i.e. DVRs are TVs that use almost as much energy as 'on' most of the time) would be easy to solve if you just made manufacturers DISCLOSE all relevant information about energy usage. You don't have to mandate minimums, standards, etc; you can solve most of this problem by giving people the information and letting them make a smart choice. For once, the usual consumer advocate nincompoops (think Consumer Reports) might even nudge people into the right direction with this.
We really need to get out of the "brute force global solution" mindset and look for local, elegant, cost effective ones.
