This weekend's launch of Apple's iPad in the US – with an international debut expected later in the month – will be a polarising moment. The television news will linger on the queues outside Apple stores, and fans will be seen drooling over these latest shiny objects of techno-lust. Doubters, meanwhile, will point out that general purpose tablet-style computers such as this have always bombed before – and if the touch-screen interface is so revolutionary, why is Apple going to sell an old-fashioned keyboard to plug into it?

To focus on issues such as these, though, would be to miss the point. This launch is about much more than just another piece of personal technology hardware, no matter how desirable. For the iPad is an extension of the most significant new development in computing since the birth of the personal computer. If it takes off, it would seal Apple's rebound to the very top of the heap in the computing world. Starting with the iPhone in 2007 and followed by the iPod touch the same year, Apple has been changing the way people relate to intelligent portable devices. Touch has become the interface and connected “app stores” the new place to find services and content.

Between them, the iPhone and the touch already represent the fastest-growing new computing platform in history, according to Mary Meeker, internet analyst with Morgan Stanley. With the iPad, Apple is now staking out a big piece of extra territory for this platform. General purpose, tablet-style devices have proved a graveyard for technology companies before. But with a model honed on the iPhone, Apple starts with a better chance than others. And even if initial sales are disappointing – as they were for the iPod and iPhone – Apple has at least outlined the shape of a big new potential market for the army of software developers who have hitched their fortunes to its technology.