Goodbye, XP. Hello, Midori

June 30 is the day that Microsoft begins phasing out Windows XP by no longer providing copies of the operating system to PC makers and retailers for preloading on new machines. It's also a good day (thanks to a recent New York Times opinion piece) to start looking ahead to what comes next -- after Windows.

That answer could be Softie Eric Rudder's mysterious "Midori" project.

First, the back story: As San Jose State Professor Randall Stross notes in his Times article, "Windows Could Use a Rush of Fresh Air," Windows has become big and unwieldy. That's why Microsoft has been working for the past several years on reducing dependencies within Windows. And that's what MinWin, the slimmed-down Windows core that Microsoft's Core team has built (which supposedly won't be at the heart of Windows 7) is all about.

Microsoft also has been investigating for the past several years what a non-Windows-based operating system might look like. That project, which recently hit the 1.0 milestone, is code-named "Singularity."

This is how the Singularity team described its mission:

"The Singularity project started in 2003 to re-examine the design decisions and increasingly obvious shortcomings of existing systems and software stacks. These shortcomings include: widespread security vulnerabilities; unexpected interactions among applications; failures caused by errant extensions, plug-ins, and drivers, and a perceived lack of robustness. We believe that many of these problems are attributable to systems that have not evolved far beyond the computer architectures and programming languages of the 1960's and 1970's. The computing environment of that period was very different from today…."

As Microsoft officials have said, Singularity -- a microkernel-based operating system written as managed code -- is for research purposes. Microsoft has no plans to commercialize it.

But what Microsoft hasn't discussed publicly -- which I address in my Microsoft 2.0 book -- is that Microsoft is working on a derivative of Singularity, code-named "Midori," which could end up seeing the light of day somewhere down the line. From Microsoft 2.0:

"There's a seemingly related (related to Singularity) project under development at Microsoft which has been hush-hush. That project, codenamed 'Midori,' is a new Microsoft operating-system platform that supposedly supersedes Windows. Midori is in incubation, which means it is a little closer to market than most Microsoft Research projects, but not yet close enough to be available in any kind of early preview form.

"What's also interesting about Midori is who is running the project. One-time Gates heir-apparent Eric Rudder is heading up the effort. Midori is being incubated under Chief Research and Strategy Officer Craig Mundie's wing. 'Everyone under him (under Rudder on Midori)  is a multi-year vet, has a super fancy title, and is going back to their roots and writing code like they probably did in the old days,' one Microsoft tipster told me.

"When and how Microsoft will roll out Midori is still a mystery. But it sounds like the company thinks the project is serious enough to dedicate a considerable amount of time/people/resources to it."

I tried asking the Singularity team about Midori earlier this year and got a very nervous looking "no comment" in response.

Anyone out there have any more to share on what Midori is?