"PCs are being replaced at the center of computing not by another type of device—though there’s plenty of excitement about smart phones and tablets—but by new ideas about the role that computing can play in progress," says Mark Dean, IBM Middle East and Africa chief technology officer. "These days, it’s becoming clear that innovation flourishes best not on devices but in the social spaces between them, where people and ideas meet and interact." 

"I, personally, have moved beyond the PC as well," he says. "My primary computer now is a tablet." While PCs will continue to be much-used devices, they’re no longer at the leading edge of computing, he argues. "They’re going the way of the vacuum tube, typewriter, vinyl records, CRT and incandescent light bulbs."

There are several ways those statements might be viewed, and they illuminate the broader sources of value within all of computing these days."Computing is changing," says Forrester Research analyst Sarah Rotman Epps. So what does “post-PC” mean, anyway? It might not mean that consumers and businesses no longer buy devices recognizable as personal computers.

Forrester Research forecaststhat even in the United States, a mature market, consumer laptop sales will grow at a cumulative average growth rate of eight percent between 2010 and 2015, and desktop sales will decline only slightly. Even in 2015, when 82 million US consumers will own a tablet, more U.S. consumers will own laptops (140 million). Read more here.

But the issue is only partly about hardware form factors. Rotman Epps argues that one evolution is from "stationary" to "ubiquitous" computing; formal to casual; arms-length to intimate; abstracted to physical. Ubiquity is illustrated by widespread use of smart phones and tablets. Casual computing is illustrated by brief episodes of computer usage, between "doing other things."

"Intimate" use means all the ways people interact with computing devices other places than sitting at a desk or table. "Physical" is shown by touch screen or sensor interaction with a computing appliance.

In addition to those changes, some might say "the post-PC era is characterized by an explosion of ideas and application of new talent to software." That, in fact, might be the biggest change. Read more here.

People do different things with computers than they used to, and that is what allows and enables use of different form factors and devices. In decades past, though it was not actually true that we used a  "one size fits all" approach to devices (some terminals were optimized for graphics, others for mobility, for example) the basic approach was to support all use modes with one type of device. 

What smart phones and tablets have shown is that people now use applications in ways that allow different approaches to hardware and devices. Where in past years the "most powerful" devices might have been issued to, and used by, top management, that is reversing. These days, most top execs actually consume content more than create it. In that use scenario, a tablet is a suitable and preferred choice. 

The same thing is generally true of consumers as well, most of whose usage these days consists of content consumption, with only a light bit of texting, emailing and quick social network posts as the primary "content creation" activity. Under those conditions, devices optimized for content consumption makes lots of sense. 

One might be tempted to draw other lessons as well. The reason access service providers worry so much about their value in future ecosystems is precisely because so much of the end user value is provided by the over-the-top applications, and far less by the "bundled" applications, as was true of voice or video entertainment services, for example. As tablets and smart phones have become more important platforms precisely because it is the "consumption," not the "creation" that is the key requirement, so access to the Internet is necessary, but provides little inherent value beyond the fact of access. 

Applications and content consumption has changed device requirements. Applications and content consumption also likewise change the value of "access." The access remains essential. Beyond access, nearly all the value end users derive is from the applications which can be used. 

The "PC" era might be "over," but in a similar way also the era where "communications" meant "telephone" or "voice" or "voice provided by a telephone company" era might be said to be "over." As with PCs, voice will continue to be useful and highly used. It's just that lots of other applications and use modes also have emerged. As Dean argues that the PC is no longer at the forefront of innovation, so voice generally is not at the forefront, either. 

As "computing" now encompasses far more than PCs, so "applications and experiences" now encompass much more than voice. We might be "post-PC," or getting there. We might also be post-voice, or getting there.