Tech pundits and enthusiasts will be debating the new Windows shell and user experience for months to come, but the biggest news out of last week's BUILD Conference, from my perspective, was the thorough "Windows Phone-ification" of Windows 8. As one of the few fans of Microsoft's under-appreciated Windows Phone, I view this as great news—because even though the rest of the world has ignored Windows Phone, the software giant has been busy building a superior smartphone platform.

And now it's all coming to Windows.

Early last year, when Microsoft unveiled Windows Phone to the world, I called two people: a friend from the Windows Phone team and my publisher. After ensuring I'd have early access to a device (the first call), I told my publisher I had a new book to write. I went into this project knowing two things. First, I would make almost no money writing a book that very few people would read. Second, this was fine with me because it would be a great way to really immerse myself in a mobile platform after focusing primarily on desktop and server computing for 15 years.

Both of my predictions held true, and the 17 people who did buy Windows Phone Secrets hopefully appreciate the effort involved. But I discovered something writing this book that surprised me. Yes, there were issues with the software—there always are, and this was a 1.0 release after all—but I never experienced that post-demo despair, when the product that looked so great in theory steadily falls apart after real-world usage. (This is a classic problem with most technology products, in my experience.) Windows Phone had some functional holes, don't get me wrong. But it was also a wonderful foundation.

Just as important, Windows Phone wasn't an iPhone clone (cough, Android), and it wasn't different just to be different. It was, instead, better. Thoughtfully designed for humans. I've written a lot about Windows Phone here and elsewhere, so I won't bore you with the full evidence of this again, but let me give you just one great example. On an iPhone, if you want to look at photos, you have to manually find and then navigate in and out of multiple apps—Photos, Facebook, Flickr, MobileMe Gallery, and so on—one at a time, manually. On Windows Phone, you just go to the Pictures hub. All your photos are there, whether they're on the phone or stored in various online services. In this way, Windows Phone works like you do (photos are in a single location) rather than forcing you to think like it does. (Was that photo in Facebook or my camera roll?)

What can I say? I fell in love with it. The fact that the world has ignored Windows Phone, at least so far, is tragic. But that's going to change. And it's going to change because Microsoft is bringing a Metro-style user experience to Windows and replacing the creaky Windows shell with a new hotness. That new shell is sitting on top of a completely new Windows runtime, WinRT, which—surprise, surprise—uses a next-generation version of the application packaging Microsoft first created for Windows Phone.

We’re only just beginning to understand the ramifications of this change, and although most people are still fixated on the surface-level UI stuff, I think the most significant changes are below the surface. Windows 8, like Windows Phone before it, sandboxes new apps from each other and from the OS. There’s no arbitrary way for an app to access the file system: Instead, the user must OK any such access, either explicitly—via a cool new full-screen notification—or implicitly through a File Picker. You won't be able to write a virus with WinRT. And you won't be able to create a poorly written app either, because Microsoft is going to carefully curate its new Windows Store, which will be the only place such apps can be installed (in seconds) to Windows 8. Just like on Windows Phone.

(Classic Windows applications can still be found in the usual places, and of course Windows 8 is backward compatible with anything that works with Windows 7. Including viruses.)

Walk through that pretty Windows 8 UI and you'll see a bunch of familiar terminology, assuming you're a Windows Phone junkie like me. Live tiles sitting on a Start screen. A rich Lock screen with notification icons. A Windows Phone–like PIN password option (and an even cooler Picture password). Secondary tiles so that apps can pin "interior" functionality; an email app might let you pin a particular email folder, for example. Integrated search, for files, apps, and information inside apps. Location services. On and on it goes. The line isn't just blurring, it's disappearing.

Indeed, my sources tell me that the line really is disappearing and that the next major Windows Phone version, due in late 2012, will in fact be based on the Windows 8 code base. (Windows Phone 7.5 should ship sometime very soon and is a minor update to the initial version.) This too will have some interesting ramifications, if true, although I think it's clear that Windows Phone will evolve to pick up some of the improved Windows 8 functionality—better configurable live tiles, for example—regardless.

But consider this little possibility: Right now, centralized mobile device management is kind of a mess, with serious server requirements and a set of capabilities that vary from device to device. But what's the most configurable and controllable device in an IT environment today? That's right, a PC. And if Microsoft brings the Windows 8 OS to Windows Phone, then that means you'll be able to manage those devices using the management model admins already know and trust.

Now tell me that's a future you're not excited about.