Microsoft (NASDAQ: MSFT) will offer the Windows 8.1 update, code-named Windows Blue, as a free download to current Windows 8 and Windows RT users, and will preview the operating system software on June 26 to the public, timed to its Build developer conference in San Francisco.

Last week, Microsoft starting talking more about the Windows 8.1 update, opening up a bit more—although not a whole lot more—than the sketch it first offered in March about the software. So far, Microsoft’s channel partners aren’t selling Windows 8 in bunches. Will the new update spark more channel interest? Perhaps …

Tami Reller, Microsoft Windows chief marketing and chief financial officer, told attendees at the JP Morgan Technology, Media & Telecom Conference in Boston Tuesday that Microsoft intends to offer “continuous updates to customers” of Windows.

“With Windows 8 … we really did introduce this new experience that redefined what is possible with mobile computing,” she said. “Windows 8.1 will be delivered as a free update to Windows 8 and to Windows RT and it will be easy to get right from the Windows start screen through the App Store. … This means that customers today that have Windows 8 or plan to buy a device in the near future can seamlessly get the advantages of Windows 8.1.”

Inasmuch as Microsoft wants developers to start cranking on Windows 8.1 right away, the vendor has timed the update’s public preview, available as a download, to coincide with its Build developer conference starting June 26 in San Francisco.

As for enterprise customers, Reller said that Microsoft sees “Windows 8.1 giving them that much more confidence to be able to deploy Windows 8 devices, whether that’s tablets or PCs.”

Microsoft will make the update generally available “later on in the calendar year,” Reller said, but she didn’t provide a specific target date or detail exactly what improvements users can expect to see in Windows 8.1.

After months of avoiding any discussion of a Windows 8 update, Reller last week confirmed the new software will run on more devices and address some of the criticism levied at its limitations. Yet she has not gone any farther in describing the updated OS other than to say it will “deliver the latest new innovations across an increasingly broad array of form factors of all sizes, display, battery life and performance, while creating new opportunities for our ecosystem.”

So for now, we’re left with some Windows 8.1 marketing fluff but not much detail aside from the expectation that the new OS will be more suited to small-screen format tablets and will include Microsoft’s response to Windows 8 critics, who’ve dinged it for a lack of native applications and clunky backward compatibility with earlier versions.