just like most people hadn't owned a smart phone before getting the iPhone.

Hahahahahaha! No wait, that wasn't a joke - you seriously believe that, don't you?

Most people don't own an Iphone full stop. Nokia have 40% share - and Apple have not very much. Perhaps it was the first smart phone for most Iphone users, but that tells us little - it may well be true that most Nokia owners got a Nokia as their first smart phone, and same for all other makes.

But "revolutionary to most Iphone users" isn't "revolutionary to most people". Since the Iphone has less than 5% market share, this is clearly true. At least, it would be if you relied on market facts, rather than making it up as you go along.

And can you give me a definition of smart phone that included the original Iphone, but doesn't include most feature phones? Thought not.

You seriously base your logic on "Most people haven't owned a tablet PC, therefore the Ipad will be revolutionary"? That's absurd logic. The same reasoning would apply to any non-Apple tablet too. Sorry, you don't get to be revolutionary when you're not first. The popularity argument is dubious anyway (was Windows and IE revolutionary, because it was most people's first experience?), but it's laughable to claim it to a vaporware product that isn't even released, and isn't remotely near being something that most people use.

A hearing aid is specifically designed, manufactured, marketed, and dispensed, for one and only one purpose: to treat a human disease. It is not intended to be used, nor can it safely be used, by people with normal hearing.

By its very nature, it modifies the function of the human body. It is not in any way comparable to an article of clothing, or an mp3 player, whose fit and function can be ascertained by a layman, and which can be worn or used safely by virtually anyone.

Using an improperly made hearing aid, or even a properly made one that isn't specifically prescribed for you, would certainly cause you harm, including potentially irreversible nerve damage, and hearing loss. And a layman, end-user, who bought one over the counter, is not qualified to determine whether it is functioning correctly, or appropriately for his hearing deficit. It could be producing levels at certain frequencies that cause long-term damage, and he would never know it, until it was too late. So, it is absolutely in no way analogous or comparable to a pair of track shoes, or an mp3 player.

A hearing aid is obviously a medical device, and correctly regulated as such, in my opinion, because it must be dispensed properly, and must perform correctly, or it can cause serious adverse health effects for its user.

I don't agree with the premise that a hearing aid is innocuous, and incapable of causing death or serious injury, therefore doesn't require stringent safety testing.

Given that every component of every device is subject to possible failure, I could imagine a scenario where a component failure in a defectively designed hearing aid could convert it from an amplifier, into an oscillator. Imagine that you are driving down the highway at 100km/h when suddenly, you have a 110dB tone at 2khz blasting into your ear, coming from a device the size of a pea, wedged deep in your ear canal. I could see that scenario very easily leading to serious injury, or death.

I would want to know that my hearing aid has been design validated, so that no possible failure, or combination of failures, could ever cause that to happen.

First, it's a medical device, not a commodity consumer item like a netbook, so its manufacturer must prove both its safety and effectiveness, with independent tests, before it can be licensed for sale by the FDA in the U.S., or the corresponding medical regulatory authority in other countries. That process is time consuming, and expensive. Those costs must be paid for, and are reflected in the price. Second, its technology requires extremely low power circuitry, and a much higher level of miniaturization, than a netbook. These factors too, naturally increase the cost of the device.

I stand corrected. Thanks for that explanation.

The article adresses that issue up front, stating explicitly that 90-100% of the absorbed light is converted into electricity. From the article:

Atwater and his colleagues--including Nathan Lewis, the George L. Argyros Professor and professor of chemistry at Caltech, and graduate student Michael Kelzenberg--assessed the performance of these arrays in a paper appearing in the February 14 advance online edition of the journal Nature Materials.

Atwater notes that the solar cells' enhanced absorption is "useful absorption.".

"Many materials can absorb light quite well but not generate electricity--like, for instance, black paint," he explains. "What's most important in a solar cell is whether that absorption leads to the creation of charge carriers.".

The silicon wire arrays created by Atwater and his colleagues are able to convert between 90 and 100 percent of the photons they absorb into electrons--in technical terms, the wires have a near-perfect internal quantum efficiency. "High absorption plus good conversion makes for a high-quality solar cell," says Atwater. "It's an important advance.".

The key to the success of these solar cells is their silicon wires, each of which, says Atwater, "is independently a high-efficiency, high-quality solar cell." When brought together in an array, however, they're even more effective, because they interact to increase the cell's ability to absorb light..

So, assuming their worst case figure of 90% efficiency, and 85% absorption, the overall light to electricity conversion efficiency would be ~76.5%

If this technology scales, and can be manufactured economically, it will be a tremendous breakthrough, which could deliver significant and long lasting benefits for the entire planet.