The news that HP and other computer makers are testing Google's Linux-based Android operating system on netbooks shouldn't come as a surprise to Microsoft. In fact, Steve Ballmer himself predicted it during a February discussion with analysts. The key question is whether we'll see a real ecosystem of full-fledged PC applications for Android.

As demonstrated by Windows, and now the iPhone, it's the apps that give a technology platform real appeal. The challenge for Android on PCs was foreshadowed by two VentureBeat freelancers in a January post about getting Android to run on an Asus Eee PC.

"One important part of the ecosystem would be to have a set of well-functioning applications (an office productivity suite, for example). Google is mostly leaving applications development for Android to third parties (applications which run in the browser like Google Docs being the notable exception). At the rate things are going, we don’t see enough of these third parties developing applications for Android netbooks in the next 12 months."

Of course, that could change if Google puts more support behind the concept of Android on PCs. But would it? Whenever the subject of Google's ambitions comes up, I think back to my brief conversation with Google CEO Eric Schmidt after he spoke in Seattle in 2005. I asked at the time if Google would ever try to compete directly with Windows, Office or Internet Explorer.

"We don't try to do things which people already do well," he said. "We try to do different things. ... Why would we want to take our scarce resources and do something that someone else has already done? You never want to say never, but it doesn't make sense to me."

Given the products the  company has launched since then, you can infer from Schmidt's comments that Google didn't feel Microsoft was doing an adequate job with Office or Internet Explorer. So it wouldn't be a big stretch to imagine Google taking on Windows, as well.

But the real push for Android on PCs could come from the computer makers themselves. The emergence of a strong alternative to Windows would create more competition for Microsoft, giving HP and others more leverage in their dealings with the company. In that way, it's not surprising that HP and others would consider and test Android on computers.

The interesting part now will be watching to see how far they take it.