Steve Ballmer, Microsoft’s chief executive, has hit the European press circuit in full-on tease mode. He’s talking up a new version of the Windows operating system that will cater to so-called “cloud computing” technology, where people use software that’s running in a data center rather than on their local machine.

Mr. Ballmer has mentioned this operating system, dubbed Windows Cloud, at events in London and Paris. The name-dropping comes ahead of Microsoft’s Professional Developers Conference later this month in Los Angeles.

So what exactly is Windows Cloud? Well, Microsoft won’t budge on exact details just yet.

But Dave Cutler, one of the company’s top software engineers, has spent years working on a project code-named Red Dog that some suspect will serve as the underpinning for the new operating system. Mr. Cutler has a knack for developing sophisticated code, and he may have come up with an operating system tailored to this notion of distributing software across thousands of servers and letting customers tap into all that horsepower from their home or office computers.

Google’s vast data centers rely on a modified version of the open-source Linux operating system and the MySQL database. By going with open-source software, Google can tweak code to suit its needs. In particular, Google has been able to create lightweight versions of Linux and MySQL that spread well across myriad machines.

Microsoft may now have taken a similar approach with Windows and its own SQL Server database by developing a thinner, faster version of Windows that server makers like Dell and Hewlett-Packard could offer with their systems. Presumably the new version of Windows would also make use of Microsoft’s server virtualization software, which today lets customers run many applications on a single physical system, and will soon let them move those applications around from server to server at will.

“Just as we have an operating system for the PC, for the phone, and for the server, we need a new operating system that runs in the Internet,” Mr. Ballmer said during a speech in France on Thursday. “I bet we’ll call it Windows something. We’re going to announce it in four weeks. We might even have a trademark by then. So, for today I’ll call it Windows Cloud. And Windows Cloud will be a place where you can run arbitrary applications up in the Internet. . .”

I’ve done a search through Microsoft’s trademarks, and, as Mr. Ballmer indicated, there doesn’t appear to be a name for the software.

Fluffy Windows, anyone?