For 15 years there had been a steady drumbeat about the coming age of wearable computers.

Construction workers, engineers and countless other professions would be revolutionized by this new paradigm in computing technology. Worn on the head, or strapped to an arm or torso, these machines would provide technical schematics as needed and allow users to record and enter data without having to lug around a cumbersome laptop. Heads up displays and simplified keyboards would provide workers all the benefits of a traditional PC without having to carry one around.

Science fiction writers couldn’t get enough of it.

Yet for all the fanfare and countless press photos of models and grad students wearing such devices strapped to their heads and arms, the wearable computer revolution has yet to arrive in force. So what happened?

In terms of performance in the private sector, the wearable computer became a victim of its own hype. Small technology start-up companies in the late 1990’s were tossing around all kinds of buzzwords, and wearable computing was only one of several futuristic-sounding technologies that venture capitalists financed. Sadly, they understood the concept just as poorly as they understood the Internet.

Wearable computer firms quickly went public and garnered much attention, like the Virginia-based Xybernetics, which promised a complete line of wearable computers for everyone from doctors to soldiers to engineers. But like many other tech start-ups of the era, Xybernetics was all promotion and had little actual substance. After thirty-three straight quarters of losses, Xybernetics filed for Chapter 11 protection in 2005. The few wearable computers the company did produce had many reported technical problems. The company emerged from bankruptcy protection earlier this year, with a much reformed business plan. Other start-up firms that specialized in wearable computer technology saw similar fates, or were bought out by larger tech companies.

While wearable computers produced a few start-up flameouts, those failures should not reflect badly on the technology. In fact, despite their limited acceptance in industries like construction, wearable computers are finding uses in the aerospace industry and hospitals. While predictions of gadget-laden cyborgs plodding around offices and construction sites did not pan out, the basic idea is very much alive.

In the last decade the technology has been moving away from the stereotypical garish, cable-sprouting plastic bricks, to sleeker shapes.

“I never liked wearable computers in the design of a brick ,” says Asim Smailagic, research professor at Carnegie Mellon University, and a leading developer of wearable and pervasive computer systems. “Lots of wires are not appealing, and can get in the way.”

“The form factor of a computer built into a watch is good step. Small computers that can be worn on the belt are also a good option. What I would like to see is for the computers to be ever-present, but no one ever has to see them.”

Smailagic has worked on several revisions of Carnegie Mellon’s groundbreaking VuMan wearable computer, first introduced in 1991. Equipped with multiple data ports and a simple heads-up display over the user’s eye, it allowed one to view schematics and other technical data by manipulating a belt-mounted control. “VuMan was part of the master-apprentice style, where the computer provides a plan so the person can perform a task they are not able to do without help,” Smailagic says. Such devices sparked much of the initial private-sector interest in the field, but Smailagic believes that wearable computers have moved beyond the simple master-apprentice interface. “We have been working for several years now on context awareness, where the computer acts as a ‘virtual coach’ and gives advice based on what it senses about your motion and environment... What we want is for these computers to be like a flashlight: you turn it on and it works. Nothing gets in the way of accomplishing your task.”

So while the wearable computer of wires and awkward headsets may have gone out with the Internet boom, the work continues and many of the ideas have shown up in other portable electronics. For a newer version of the VuMan, the developers switched to a dial-based input system, because it was easy to operate out of sight. Anyone familiar with the scroll wheel of any iPod can tell you how much better it is than a keypad for certain operations. Lightweight laptops and tablet style PCs are inspired by many of the wearable computer ideas about interface and the usefulness of having a highly portable computer at all times. And with versatile cellphones that can take digital photographs, browse the internet and link up with a wireless Bluetooth headset, it would appear the wearable computer did arrive, only you have to hold it in your hand.

Many of the best ideas and philosophy of the wearable computer have already been adapted or poached by other technology manufacturers. While you don’t see many people on construction sites wearing heads-up displays and typing into a hiptop keyboard, they are using small handheld PDAs to keep track of their work, and cellphones are ubiquitous. There is still much to be gained from pursuing computing devices that are omnipresent and completely transparent, but the old stereotype of clunky, heavily wired wearable computers is long gone.