UNLESS you have been holidaying on Mars, you will have gathered that Apple launched a new version of its iPad on March 7. They’re refusing to call it the iPad3 but everyone else is. I’d be more inclined to call it the iPad2S, following the nomenclature the company has adopted for its mobile phones.

That’s because, no matter how the Apple Reality Distortion Field spins it, the latest iPad is really just an evolutionary advance on its predecessors.

Granted, it has a significantly better display, a more powerful processor (therefore better graphics performance), a better camera, which will record HD video, and a wider range of mobile connectivity options. But otherwise, it’s the mixture as before - though that didn’t stop the Apple website being swamped, presumably by folks anxious to pre-order the newest new thing.

The presentation was led by Tim Cook, Apple’s new CEO, who had one fascinating slide. It showed that in the last quarter Apple had sold 15.4 million iPads. In the same quarter, Acer, Dell, Lenovo and HP - the world’s four leading manufacturers of PCs - sold 9.8 million, 11.9 million, 13 million and 15.1 million PCs respectively. This demonstrates, Cook declared, the extent to which we have moved into a “post-PC” world - a world which, he implied, would continue to be dominated by Apple. As evidence, he claimed that sales of post-PC devices (iPad, iPhone and iPod) accounted for 76 percent of Apple’s revenue during that quarter, and that it had sold more than 172 million of these gizmos in total last year. In comparison, all PC makers combined shipped about 350 million PCs in the same period.

So are we indeed entering a “post- PC” world? Most of the attention at the moment is focused on trying to predict the “crossover point” - when the graph of rising tablet sales intersects the curve of declining PC sales.

Estimates of when that will happen range from 2013 to 2017 or even later.

But even when the crossover happens, it still won’t signal a post-PC universe, for a variety of reasons.

Sales of new devices, for example, ignore the fact that there is a colossal number of PCs in the world, most of them owned and operated by businesses whose purchasing decisions are very different from those of individuals. To date, the iPad frenzy has been mainly a consumer phenomenon. That doesn’t mean companies aren’t buying and deploying tablets, just that they’re not doing it at the same pace as consumers are. And their huge investment in what Apple might disdain as “legacy” systems - large networks of PCs running Microsoft Windows - means that a move to tablets would require radical changes in their IT infrastructures.

Companies won’t make those changes lightly in a tough economic climate, especially if their boring old PCs are providing a “good enough” service - which most probably are.

Besides, there is another variable in the equation that wasn’t much talked about. Microsoft released the public beta (ie test) version of Windows 8, the latest version of the venerable operating system. Why is this relevant? Well, history suggests that whenever Microsoft releases a major upgrade to Windows it triggers a spike in PC sales, as companies use the release as a trigger for system upgrades. Some industry observers think that Microsoft will sell more than a billion Windows licences over the next three years. If that happens, we might see a temporary reversal in the decline of PC sales - thereby pushing Mr Cook’s crossover point further into the distance.

Predictions of a post-PC world are just the latest example of what the computer scientist John Seely Brown calls “endism” - the idea that a new technology signals the end of an older one. The reality is more mundane. While the newcomer does indeed disrupt things and take over parts of the ecosystem, the established species adjust and retreat to the habitats where they have significant advantages.

The iPad is great for some things, but hopeless for others. I’ve had one since its launch in 2010 and I use it every day.

It has a terrific battery life, springs instantly to life when opened, is robust and portable and, when fitted with a sim card, provides good connectivity on the move. One could, I suppose, try to write a book, edit a movie or build a big spreadsheet model with it - just as one could, in principle, dig the garden with a teaspoon. But you’d be mad to try.

The truth about computing is like the truth about steeplechasing: it’s always horses for courses.