That number might not seem like much compared to the gazillion apps at Android Market or Apple's App Store, but those 20,000 apps answer a question on many techies' lips this week: Why didn't Nokia pick MeeGo? Windows Phone Marketplace passed the 20k threshold about a month ago.

The N9's unexpected launch on June 21 was one of the most perplexing mobile phone announcements in recent memory. The N9 is a stunning piece of hardware that runs smart-looking software -- MeeGo 1.2. But Nokia has all but abandoned MeeGo and Symbian, which despite market share declines is still the most widely used mobile operating system on the planet. The N9 had lots of gawkers drooling over its sexiness but disappointed that with MeeGo there's no point.

MeeGo was supposed to be Nokia's future before CEO, and former Microsoft divisional president, Stephen Elop cut the Windows Phone distribution deal earlier this year. Instead of a slow transition from Symbian to MeeGo, Nokia would fast-track to Microsoft's mobile OS.

Nokia's other MeeGo phone is the N900, and the selection of apps is meager at best. The company's Ovi Store, serves up 90-top free apps, 88 bestsellers and 166 new ones for N900, with the latter category actually looking like the entire selection available. By comparison, the number of apps available for Windows Phone is simply enormous. Microsoft has developers, and they're working the apps. Remember, that Windows Phone only became available in autumn with about 1,000. Less than two months ago, the number was 18,000. It was 20k in late May. Who knows, 25,000 may be close coming.

I used to own a N900. It was a brick, but I still loved the smartphone. It had real character, and MeeGo was a major reason why. There was something quite different about using the N900 compared to iPhone or any Android handset. The N900 felt more like a pocket computer, and MeeGo provided dramatic capabilities. I still miss N900.

But platforms need applications. Either the phone's manufacturer provides them or third-parties do -- and ideally both. MeeGo doesn't have much from either. Nokia is really good at doing hardware but long hasn't been able to compete on software and services. From that perspective, the Microsoft marriage has potential.

The questions now: How long before there are 25,000 apps, and what will the number be when the first Nokia Windows Phone ships. Earlier this week, Elop quietly showed off the first prototype -- "Sea Ray" -- and of course it leaked out right away.

Microsoft doesn't need hundreds of thousands of apps for Windows Phone to succeed. The platform just needs enough of them. Which ones is more important than how many. Still, larger number has marketing value for both potential customers and developers.

That said, compared to Android Market and App Store, 20,000 doesn't seem like much. They offer more than 200,000 and App Store 450,000 apps, respectively.