If – and for some, this is a big if – the iPad is a PC, then Apple is about to overtake HP as the world’s leading manufacturer of PCs, reports industry research firm Canalys. But the the truth is that Apple has already taken this title.

First, let’s address the issue of whether or not a tablet is a personal computer. (Just spelling out “personal computer” makes the whole debate seem absurd.) iPads are more powerful than laptops were even a few years ago. Sure, they’re running ARM chips, but now that ARM chips are running, oh I don’t know, servers, it hardly seems to matter what hardware you’ve got under the hood as long as it gets the job done.

More importantly, once you attach a keyboard to an iPad, the “this isn’t a PC” line doesn’t pass the sniff test. As I can attest from hundreds of hours of personal experience, an iPad nestled in a Zagg keyboard case running web apps in Safari is indistinguishable from a laptop, and certainly more versatile than Google’s Chromebook.

Granted, it’s annoying that some of the handiest keyboard controls (for tab and application switching, for example) don’t work. Which just illustrates the point that it hardly matters whether or not the iPad is a particularly good PC. In confusing “this is a PC” with “this is a laptop replacement,” technology pundits continue to miss the forest for the trees, which is that what people want out of a PC turns out to not really be what companies thought they wanted.

There’s no reason an iPad couldn’t multitask to a greater extent than it currently does. If it wanted to, Apple could enable greater keyboard control and faster application switching.

Some apps, like Blogsy, already allow a degree of multitasking most people think would be impossible on an iPad. (For one, Blogsy allows you to browse the web and image libraries while writing posts in a split screen mode, effectively allowing you to have an HTML editor, web browser and image editor all open at the same time.)

Which brings us full circle on the status of Apple as PC manufacturer. The iPad is hardly a post-PC device – that’s marketing speak. It’s a PC in a form factor that’s the natural evolution of the ongoing press for ever smaller and lighter devices. If you hack it, you can do just about anything you like with it.

The real question is not, “is the iPad a PC?” The real question is, “at what point do we start defining devices like the iPhone 4S, which has the same CPU as the iPad and the same screen resolution, as PCs?” (Not to mention devices like the Motorola Atrix / “lapdock” combo.)

In which case, Apple is, bar none, the world’s largest PC manufacturer.