This week Microsoft finally began talking about what it coyly refers to as “the operating system code-named 'Windows 8.'” (Spoiler alert: “Windows 7” was originally a code name, too.)

Windows boss Steven Sinofsky sat down for an interview with Walt Mossberg. Windows Experience VP Julie Larson-Green gave a demo of the new “touch first” Windows 8 interface, and Microsoft published its own promotional video.

Here’s my reaction: You ain’t seen nothin’ yet.

Seriously (and more grammatically), we really haven’t seen much in these videos. In particular, there are no clues as to how the traditional Windows desktop will evolve. That market will continue to be hugely important, both in businesses and among home users, and I expect to see some similarly eye-catching innovation in the Windows 8 desktop experience.

But the single most common objection I’ve heard to Microsoft’s strategy is that putting Windows on a tablet is a recipe for failure. During the All Things D interview, Walt Mossberg raised that question directly:

Mossberg: I’m not a coder by any means, but I’ve always been told Windows is this gigantic, enormous thing, with all this legacy stuff that you’ve had to keep in there. Why would you turn to this big heavy Windows thing…?

Sinofsky’s answer, in part, pointed out that during the transition from Windows Vista to Windows 7 Microsoft’s developers “looked really hard at this, and we just said, ‘Wow, we can do a bunch of work so that we don’t need to change the system requirements for the release.’” For Windows 8, the system requirements will remain the same.

In theory, that means a five-year-old system purchased when Windows Vista went on sale in January 2007 will be able to run Windows 8 well. That's remarkable.

I’m not surprised, though, and to me this is the clue that explains why the “gigantic, enormous” Windows 8 will be able to run on low-end tablets.

Remember MinWin? Back in 2008, some people were wondering whether Microsoft was planning to radically downsize the Windows 7 kernel. They did a good job of slimming it down, but I’m convinced the real work will appear in Windows 8.

For the evidence, go back to a post I wrote in March 2008, while Windows 7 was still a code name: Is MinWin really the new Windows 7 kernel? Be sure to look carefully at the details, like this quote from Microsoft Distinguished Engineer Eric Traut’s presentation on virtualization technology in 2007:

A lot of people think of Windows as this really large, bloated operating system, and that may be a fair characterization, I have to admit. It is large. It contains a lot of stuff in it. But at its core, the kernel and the components that make up the very core of the operating system actually is pretty streamlined.

Yes, Walt Mossberg’s characterization of Windows was accurate. In 2007.

Traut continues:

It’s still bigger than I’d like it to be, but we’ve taken a shot recently at really stripping out all of the layers above and making sure that we had a clean architectural layer there, and we created what we call MinWin. Now, this is an internal only - you won’t see us productizing this - but you could imagine this being used as the basis for products in the future. This is the Windows 7 source code base, and it’s about 25 megs on disk. Compare that to the four gigs on disk that the full Windows Vista takes up. [emphasis added]

A 25 MB kernel? A clean architectural layer? Add a tightly coded graphics subsystem and a new shell—like the one Microsoft showed off at D9 yesterday—and you have a serious contender. Especially when you have Moore’s law on your side.

I think there’s another clue in Julie Larson-Green’s article, Previewing “Windows 8,” which appeared on Microsoft’s website yesterday:

Today’s demonstration followed our announcements earlier this year about Windows 8 running on System on a Chip (SoC) processors, and our browser engine innovations and significantly increased standards support in Internet Explorer 10. Windows 8 extends these innovations and reimagines every level of the Windows architecture — the kernel, networking, storage, devices, user interface — all building on the broadest and richest ecosystem of software, peripherals and devices.

Anyone who thinks that the “touch first” Windows 8 interface will just be another layer on top of an old, bloated Windows code base is in for a surprise. If they’re a Microsoft competitor, they’re in for a rude shock.

So when do we know for sure?

So far, Microsoft is following the exact same launch playbook we saw for Windows 7. Bill Gates and Steve Ballmer were onstage for the All Things Digital (D6) conference in May 2008, where they previewed Windows 7 touch technology and kept the rest of Windows 7 under tight wraps.

It wasn’t until the Professional Developers Conference in late October of 2008 that Microsoft unveiled Windows 7 in full. This year they’ve scheduled the BUILD conference for September 13-16, where Microsoft will undoubtedly do a similar reveal.

I can’t wait.