If you consider the primary business of companies such as Apple, Google, Nokia and Amazon, there's not an obvious crossover.

Two of them make most of their money selling physical objects, while one sells online advertising.

Only Amazon is a proper marketplace; agnostic in terms of what it sells but caring about volume, presentation and its customers' trust.

That's the main reason the company's decision to dip its toes into the swirling app store waters, specifically a store based on Google's Android operating system is such big news.

Opening the doors

As everyone knows - and despite Google's recent expansion of paid support for its default marketplace - Android Market is designed to be the Emmental of app stores.

A bit cheesy and with plenty of holes in it, it's less a store and more a framework for OEMs, operators and whoever else to brand up and plug into their existing billing, promotion and delivery infrastructure.

And with 114 million credit or debit cards connected to its online store, Amazon certainly has the power to supercharge its version of Android Market.

Indeed, ignoring the rumours about a colour Kindle or exactly what sort of Android device its app store would plug into, it's Amazon's huge reach when it comes to online retailing that makes its app store a no brainer.

For, as is becoming abundantly clear, what's required for a successful app store is trust between consumers and the retailer, including a decent billing mechanism, not to mention some level of content curation, and the ability to encourage one off sales to become regular purchases.

No company does these things better than Amazon, and it does them so well, the trust people have buying stuff from Amazon means they are also likely to buy Amazon branded devices to buy stuff through.

The bottomline then is, if as looks likely, Amazon takes a strong stance on what content is on its store, and how it's presented, its Android store could easily become the open platform's defacto standard.

New device inbound?

In this context, even if Amazon's first step was an Android powered Kindle, it would make sense. It seems very unlikely that this is the path Amazon would take however.

Its Kindle strategy is already going great guns and doesn't need a dedicated Android app store.

The current Kindle store is perfect at delivering e-books onto a wide range of mobile devices including iPhone and Android, while the dedicated Kindle devices themselves are elegant and perfectly designed for their task, which is reading e-books.

No. The real significant aspect of its device strategy will be just how deep Amazon decides to dig into the tablet market, as well as future proofing itself in terms being able to sell into TVs and other emerging markets.

Water, not cups

For, unlike the phone and the PC OEMs, with Kindle, Amazon has proven its ability to come up with bespoke consumer electronic it can subside not with cellular connections, but with the long tail recommendation knowledge, as well as traditional sales via its website and dedicated stores.

And if it doesn't come up with Apple quality devices, that doesn't matter either.

Just as Macs were never more than a blip in the overall PC market, in this brave new world, the quality of the app store will matter much more than what you're playing on.

After all, the thirsty man cares more about the water he gulps than the cup he drinks out of.