Amazon's new tablet does one thing best: Help you to spend more money at Amazon.com

Early reviews for Amazon's new, comparatively cheap table, the Kindle Fire are out, and they are lukewarm. Put nicely, the consensus is that the Fire does a lot for something that, at $200, is so cheap. Put less nicely: You get what you pay for.

There is one thing, however, that the Fire seems to excel at: Being a store. As Jon Philips writes at Wired, "Indeed, the Fire is a fiendishly effective shopping portal in the guise of a 7-inch slate." And that's no surprise, since it's been known for quite a while that the Fire is a loss leader, meant as a gateway to other Amazon purchases.

But with Amazon as one of only four companies competing in the Great Battle to Rule Our Digital Future (Facebook, Apple, and Google being the three others), the Kindle Fire is our best and latest clue as to what Amazon's vision for that future is: The Internet as a store -- and that store is Amazon. As Amazon continues to increase its offerings beyond Amazon.com, expect those offerings (tablets, e-readers, apps) to always in some way have the growth of Amazon.com's sales as a fundamental purpose. 

This is no great surprise -- the store is how Amazon makes money, the core of its business. And the same is true for the other three Internet giants. For Google, new products (Google+ most notably) fundamentally serve to enhance its search engine, where Google can sell valuable ads. For Facebook, new roll-outs will continue to draw users into sharing more information, which fuels its ad sales. And for Apple, hardware is the core of its business; new services and software will always contribute to the comparative advantages of Apple devices.

Where the competition happens is at the peripheries, where these missions overlap: Google makes Google+ (thereby stepping on Facebook turf), Amazon makes a tablet (stepping on Apple's turf). But even as they begin to overlap, the cores remain distinct, each presenting a different option for what the digital future could look like.

Image: Reuters.