Since Apple released its first iPad in 2010 and ushered in the so-called “media tablet” market, various platforms makers have tried, unsuccessfully, to emulate the iPad’s success and push Apple out of the driver’s seat. But with Amazon’s Kindle Fire finding success with a 7" design, or what I think of as the mini tablet, these companies are all racing to the low end of the market. There’s just one question: Where’s Microsoft?

Microsoft dramatically announced its upcoming line of Surface tablets last month. These devices will run Windows RT and Windows 8, on ARM and Intel underpinnings, respectively, and one-up the iPad in a variety of ways, including a more sophisticated OS and an integrated set of productivity-pushing keyboard covers. But the Surface is obviously targeting the iPad, with a 10.6" widescreen display. There’s no mini-Surface—not yet, at least.

Meanwhile, the rest of the market is heading to 7" devices. Samsung has been selling a variety of Android-based devices at this size for years, but it wasn’t until the release of the Kindle Fire in late 2011 that consumers turned en masse to 7" tablets. Amazon’s strategy was simple, and very typical for the company: Priced at just $200, the Kindle Fire undercut the competition by a wide margin, and by offering integrated access to the Amazon’s online services for books, TV shows and movies, music, periodicals, and more, the Fire keeps users in Amazon’s sphere of influence.

Google responded recently by announcing the well-received Nexus 7, a Google-branded 7" tablet that takes the Fire approach and duplicates it with Google-branded services instead. And as a newer device, the Nexus 7 one-ups the Fire in several areas, offering a higher-resolution screen, a faster processor, and a front-facing camera, while providing a base unit that sells for the same $200 price point as the Kindle Fire. (Google also sells a unit with more storage for $250.)

This week, a source from NPD told CNET that Amazon will respond later this year with three new Kindle Fire tablets, two at 7", that will match the display resolution of the Nexus 7 (1280 x 800), and optionally offer 4G cellular connectivity. (Amazon will also apparently offer an 8.9" Fire that runs at 1920 x 1200, as well.)

And Apple, which has supposedly opposed the smaller form factor since the release of the original iPad, is apparently now prepping its own mini iPad as well. It’s expected to sport a 7.85" display running at 1024 x 768 and cost as little as $299. (And yes, a 33 percent premium over competing devices is considered low-priced for Apple.)

So the question remains. Where’s Microsoft?

According to the company, Windows 8 and RT devices can use screens as small as 7", so there’s reason to expect that the software giant’s hardware partners will deliver ARM- and Intel/x86-based tablets this year with this form factor. And given Microsoft’s partnership with Barnes & Noble, it's further probable that one of these will be a 7" Nook-branded tablet and ebook reader.

Devices with smaller screens would need to run the Windows Phone OS and, for now at least, would need to be smartphone handsets, not mini tablets. But it’s possible—if not likely—that Microsoft will adapt its licensing terms for Windows Phone 8, which is due around the same time as Windows 8 this fall, to work on non-handset devices. This system, if mythical, would provide a semi-ideal platform for mini-tablets of 5" or 6" in size.

Ideally, Microsoft would offer its own Surface-branded mini tablet. And when you consider that the current Surface designs are, in Microsoft’s own words, only the start of a wider range of devices, such a thing isn’t just possible, but probable. But there’s no hint yet that such a thing will happen this year. Given the speed at which its competitors are moving, however, Microsoft would be wise to consider such a strategy. Clearly, mini tablets are going to be a huge slice of the market going forward.