In town for his company's annual meeting with financial analysts, Microsoft CEO Steve Ballmer surprised the crowd at the BUILD Conference this week in Anaheim, California, by closing out the day-two keynote on Wednesday. And the fiery CEO delivered an interesting and eye-opening message to those who think the company has grown too slow: Re-imagining Windows with Windows 8, he said, was the key to Microsoft re-imagining the company itself.

"You could say that if Windows 8 is Windows re-imagined, we're also in the process ... of re-imagining Microsoft, and really re-imagining around four big themes," Ballmer said during his address. "Our approach to these new opportunities is centered in Windows. It's not about doing something else. It's about broadly re-imagining Windows."

The four themes for Microsoft are new hardware form factors, which include slates and convertible tablets, of course, but also the new Ultrabook PC; cloud services; and new application scenarios that provide new opportunities for developers. "Each and every one of these things is shifting our direction, what we're doing, what we're trying to accomplish," Ballmer said, "and each and every one of them, I think, has incredible opportunities not just for us, but for every developer in the world."

What's the opportunity? There are approximately 1.1 billion PCs in the world running Windows, and more than 450 million of them are running Windows 7, the current version. Each of those 450 million Windows 7-based PCs is a candidate for Windows 8, since the hardware requirements are identical, and with Microsoft opening a new Windows Store in the next OS, the company will immediately give developers a reach that's competitive with any app store, mobile or otherwise.

And of course, PCs are just kicking the bejesus out of tablets, despite reports to the contrary: Apple might sell 35 million iPads this year, and it gets a lot of press for that. But there will be over 10 times as many PCs sold in the same time period, and while growth is comparatively slow—as it would be for such a mature product—it's still a growing market.

"This year there will be 350 million Windows devices sold," Ballmer said, using Microsoft's new term for PCs, since they now refer to both tablets and traditional PC form factors. "There is no phone, there is no tablet, no operating system on the planet that will ship 350 million units of anything, other than Windows. And that creates opportunity for developers."

The early reaction to Windows 8 has been overwhelmingly positive from both users and developers, a situation I've not encountered, well, ever. Windows 95 was obviously a huge commercial success and the launch of a new era in personal computing, and that's perhaps the last time Windows generated this much excitement with both crowds. Since then, Microsoft's influence over developers appears to have declined, but by embracing web standards and user-experience simplicity in Windows 8, everything has changed. And you can see it at BUILD: Developers are excited again.

My feelings about this show can be summed up in what I now consider my greatest tweet ever, a tongue-in-cheek reference to the TV show Archer that undercuts my real belief that Windows 8 tablets will nicely compete with the iPad and perhaps Amazon's coming Android-based tablets in what should be a more heterogeneous general mobile computing market of the future:

"Hello, Windows 8? It's iPad. You win."