You didn’t think Apple was going to have this whole tablet market to itself, did you? Technology companies, sputtering and coughing in the dust left by Apple’s iPad, are readying their own devices for what is already proving to be a rapidly growing marketplace. Market researcher IDC expects 7.6 million tablets to be shipped in 2010; by 2014, that number is projected to grow to 46 million.

With summer behind us and the holidays around the bend, we are now entering the silly season, where product introductions will come fast and furious. Here is where things stand — and where I think they will be going in the months ahead.

Already, Dell has introduced its Streak tablet device, which is — let’s be frank — basically just a smartphone for Yao Ming (the Streak’s $550 price drops to $300 if you sign up for a two-year AT&T contract). Its five-inch touchscreen puts it somewhere in between an iPhone (screen size: 3.5 inches) and an iPad (9.7 inches).

The Streak has another limitation: its operating system. Like many current and future iPad competitors, it uses Google’s Android OS. In this case, however, the Streak is using an older version of Android, version 1.6. The latest version of Android is Android 2.2 (also known as “Froyo”), so Streak gets a late pass.

Samsung is readying its new tablet, the Galaxy. It is a true tablet, with a touchscreen that measures 7 inches diagonally. When it is released in late October or early November, it too will be sold through mobile carriers — all four big ones (AT&T, Sprint, T-Mobile and Verizon), in fact. The Galaxy will run on Android version 2.2.

But even having the latest version of Android is no guarantee of success. The problem is that Android was never designed for tablets — it was designed for smartphones and other devices.

Many of the apps available in the Android Market, when scaled to fit on the Galaxy’s comparatively gargantuan 7-inch display, are not going to look all that pretty, if they look like anything at all.

In an interview on TechRadar, Google’s director of mobile products, Hugo Barra, said: “If you want Android market on that platform, the apps just wouldn’t run. (The current Android operating system) is just not designed for that form factor.”

Not that Google is walking away from tablets, mind you. There is another Android upgrade in the works (Android 3.0, a.k.a. “Gingerbread”), which may play more nicely with tablets like the Galaxy.

Google has has another OS, Chrome (not to be confused with the browser — smooth moves there, Google), which may power a forthcoming tablet from HTC and Verizon later this year.

That covers the Android waterfront, more or less.

Of course, there are other players, like Microsoft, Blackberry and Palm, now part of Hewlett-Packard. Microsoft’s Windows 7 has built-in multitouch capabilities, which makes it a good candidate for tablets. For the past year, HP has had a tablet, called the Slate, in the works; it may well feature Windows 7 inside when it is released later this year.

But don’t forget that with HP’s recent purchase of the smartphone maker Palm, it has a well-reviewed but so-far-unsuccessful operating system called WebOS. Now that Palm is in HP’s embrace, it is expected that the Slate could be made in two versions: one Windows, one WebOS.

And rumours persist that Research In Motion, the maker of BlackBerry devices, has a tablet in the works as well.

That is the lay of the land for now. The question is, how is this all going to shake out? To try to answer that, consider the contours of three other tech marketplaces: those for the PC, the smartphone and the digital music player.

Not so successful

Much as Apple would like it happen, the iPad will never achieve the dominance that the iPod managed to attain. On the flip side, the iPad’s success and head start mean that it is unlikely that Apple will retreat to single-digit market-share numbers like it has with PCs (see also: Apple’s learned lessons from being a big player in PCs in the ’80s to a niche player today).

My bet is that the tablet universe will resemble something like the smartphone market, but with a dash of the PC market added for seasoning. A few platforms will divide the known world (a la smartphones) but, more like PCs, the distinguishing features will happen at the software — not hardware — level.

For starters, design is less a factor for tablets than in the other categories. A tablet is supposed to be a mostly featureless panel of glass: that is the whole point. The hardware will also be fairly standardised (display, cameras, microphone, chipset). The only question will be who has the most and best apps.

And if that is the key (and it is), then consumers are not actually the people that tablet makers should be concerned about right now — it is the app developers. Win them over, and the shoppers will follow.