The extent to which the FDA makes US food crappy is ludicrous.

And you know this because you've read the relevant sections of 21CFR? I actually have, and I can tell you that the FDA does not for the most part force food to be crappy. In many cases it allows food to be crappy by setting standards primarily for safety rather than quality, but most kinds of food can be produced to higher standards than the FDA minimum. There are only a few cases- cheeses aged for less than 60 days and made with unpasteurized milk being the most commonly given example- where the FDA gets in the way, but they're the exception rather than the rule. And, BTW, the FDA is not the relevant authority for meat, which is regulated by USDA.

Whether it makes more sense to have a central DC power supply or to have wall warts depends on details like the relative efficiency of the central power supply vs. wall warts, the voltage and current you're using, and the length of wires. Using a central power supply is only advantageous if it has a substantial efficiency advantage over individual converters. Otherwise the efficiency gains will be eaten up by resistive losses.

The ease of low voltage power is probably better than you think. The systems are supposed to be separated, but that separation doesn't have to be very substantial. They make raceways with two channels so you can have both power and signaling wiring without having to install completely separate raceways. There's also stuff like NM-S cable, which is specifically designed to maintain that separation while making installation easy. And at least under US rules, limited power wiring has much simpler installation requirements; it doesn't need the same degree of protection that power wiring does.

I assume Ovens can do the same?

You should assume no such thing. LEDs have a very serious problem with damage from heat. Fluorescent lights have a similar, though not as severe, problem with heat. Incandescent bulbs, which rely on heat to generate light, are fine with high temperatures. Unless you're going to go with a fiber optic system so the lights are far from where they're used, incandescent lighting is the only practical option for ovens.

How often do you see LED traffic lights with dead pixels, so to speak? I see that all the time.

That's actually by design, at least in part. Burned-out traffic lights are very expensive to replace; the cost of labor and equipment dwarfs the cost of materials. So the LED traffic lights are designed with many individual lights so that they'll burn out gradually rather than suddenly. That gives the maintenance people plenty of advance notice when the light will need replacement. It's a good bet that those lights have also been operating around the clock for many years before they get raggedy the way you describe them; the LEDs have expected service life of many tens of thousands of hours.

The newer Cree 100W equivalent bulbs are a bit bigger than a 100W incandescent (A21 rather than A19), but they'll still fit in most fixtures. And they use 18W for 1600 lumens vs. 26W for most CFLs, which is a substantial improvement in efficiency. You can find smaller ones that are a little bit less efficient from Philips or Feit. These are all available at Home Depot, so it's not as if they're exotic technology. You can get even more efficient ones (albeit at much higher price) if you look on Amazon.

You need to be careful about wiring for DC. Most stuff that uses DC operates at between 5 and 12 volts. If you want to drive something that uses real power, that means a high current and high resistive losses unless you use very big wires. A separate DC power system might make sense if you're going to use higher voltages- which you can do for lighting- but it's a crazy idea for 5V USB power. You'd be much better off getting one of those AC outlets that includes a DC power supply and USB charging sockets.

I don't fully agree with your ballast figure not being included either

Those figures are specifically for fluorescent tube lights, which have an external ballast. The nominal wattage of those lights is always given for the light alone, with the ballast adding 10-15% to the power consumption. Similarly, the lumen rating is for the tube by itself, not all of which makes it into the room the fixture is supposed to be lighting. In comparison, the figures for the Cree fixture are for power in and light out of the fixture, so those losses are already factored in.

I have some LED lights around and they have their place but in my opinion, they are not cost effective yet.

For a home user who has them on for just a few hours a day, that may well be true. But they're enough more efficient than fluorescent lights that they're already a good choice for places that leave the lights on all the time, and unsurprisingly that's where they've been targeted. In the longer term, the prices have nowhere to go but down as production ramps up.

Meat thermometers connected to oven controls have been around for a long time. You put the thermometer into the thing you're cooking, connect it to a socket inside the oven, and set the oven to give an alarm when the food reaches the desired temperature. The hardest part is designing it so you don't burn yourself on the oven when using it.

Fatal LED bulb problems: They aren't available in 1600 lumen (100W equivalent) in standard bulb sizes

You need to shop around some, then. There are plenty of 1600 lumen LED bulbs out there. I have ones from Cree, Feit, and XLedia, and I've seen ones from both Sylvania and Phillips for sale. The XLedia is even available in a 2000 lumen model that is safe for use in completely enclosed fixtures. It's crazy expensive, but that's the price you pay for being an early adopter.

The catch is that you have to re-wire the fixture and bypass the old ballast module.

Not anymore. Cree recently came out with a design that is a direct replacement for T8 fluorescent tubes; you can plug it into an existing fixture without needing to bypass the ballast. It's supposed to give 100 lumen/watt with a CRI of 90, which is very good, and they're selling for about $30/each.

There's a good reason people are looking so hard at LEDs rather than CFLs; LEDs are simply better technology. The best LEDs have much higher luminous efficacy than any fluorescent. For example, Cree is selling LED fixtures that put out around 125 lumen/watt vs. just under 100 lumen/watt for the best fluorescent lights. It's actually more lopsided than that sounds, because the LED figure includes all the losses, while the fluorescent is for light coming out of the tube, not the entire device, and it ignores the power consumption from the ballast.

LEDs also have a lot more potential because of their form factor and light distribution pattern. Individual LEDs are tiny so it's possible to use them in places that would be too small to put a similarly powerful incandescent or fluorescent light. They are also moderately directional, which is great when you want directional light (e.g. recessed or ceiling mounted lights) and can be worked around by using arrays shining in all directions when you want non-directional light. LEDs are really going to take off when they're used in purpose-designed fixtures that take full advantage of their unique characteristics rather than being made into awkward designs intended to be direct replacement for incandescent bulbs.

Also, to be even more nit picky, most home stoves and ovens are on 120/240V power rather than straight 240V. That is to say that they have both hot legs and the neutral of the power distribution, so they can support both 240V loads leg to leg and 120V loads leg to ground. The lights in the oven are probably running at 120V rather than 240V.

Actually, a lot of serious/professional cooks are buying exactly the kind of extremely fancy cooking gear Myhrvold likes talking about. This stuff got started because there are things that are much easier to prepare with the right technology, and high-end restaurants thrive on providing things that other places can't. Professionals have been the driving force behind sous vide cooking, for instance.

I don't honestly know, because it lasted long enough that I don't remember exactly where and when I bought it. I assume it was more than 4 years, because I moved about 4 years ago and I hadn't replaced that bulb since moving. I've replaced a lot more energy saving lights because I wanted to adopt new technology- I've recently been replacing my compact fluorescent bulbs with LEDs- than because they failed.

That said, compact fluorescent bulbs can have problems. Some of the cheaper designs only work properly when the base is down and can have a drastically reduced life otherwise. They can be damaged by dirty power. And I had a lot of problems with mine when I had them in a fixture with a ceiling fan; running the fan seemed to greatly reduce their lifespan, probably because of mechanical stress. There certainly seems to be a big advantage to paying a bit more for high quality ones.

They do already host this on their own, but putting it on Wikimedia Commons makes it easily accessible to people who want to use it for articles in any of the Wikimedia sites (e.g. Wikipedia, Wikiquote, etc.). Also, by doing an official upload, they reduce the chance of somebody claiming the files are illegitimate. This is basically a courtesy to Wikimedia.