As many expected and hoped, Microsoft is going to make the coming Windows Blue update to Windows 8 free for existing Windows 8 and Windows RT users.

Microsoft's Windows Chief Financial Officer Tami Reller, during an appearance at the May 14 JP Morgan Technology, Media & Telecom Conference, shared the pricing news.

Reller also acknowledged what those who've downloaded leaked builds of Blue have known for a while: Windows Blue is Windows 8.1 .

Windows 8 is currently available via a handful of SKUs -- Windows 8, Windows 8 Pro, Windows 8 Enterprise and Windows RT (not exactly Windows 8, but part of the family). She didn't provide more information about plans for the coming Blue SKUs.

Reller also said today that Microsoft now has more than 70,000 Metro-Style/Windows Store apps in the Windows Store. She also noted that the final version of Windows Blue (both the Windows 8 and the RT flavors) will be made available to customers through the Windows Store once they are available.

Last week, Reller acknowleged that Microsoft plans to have Windows Blue available by holiday 2013 . (I continue to hear the release to manufacturing will be around August 2013.) Julie Larson-Green, the head of Windows engineering, also confirmed last week that Microsoft plans to make a public preview of Blue available by the end of June, 2013 , around the time of the Microsoft Build 2013 conference. Reller reconfirmed the preview date today, noting the Blue preview will be out at Build, which kicks off on June 26. (I've asked Microsoft if Windows RT/Surface RT users will get the preview, too. The answer is yes, as a new Microsoft blog post mentions in its last line.)

Last week, Reller wouldn't talk about Windows Blue's price . She said Microsoft planned to disclose more about pricing and the SKU line-up for Blue before the end of May -- which set off a chain of angry reactions among some Windows 8 users who thought the word "pricing" meant Microsoft definitely planned to charge for Blue. But a mention of Blue being a free upgrade by All Things D's Walt Mossberg in an article from late April made me believe free was the plan.

Reller emphasized that Microsoft's strategy in using the Windows Store to deliver Blue is focused around giving users choice about when they deploy the coming update.

"Windows 8.1 will be a packaged set of updates which customers can say when they are ready (to deploy)," she said.

Reller also was asked during a Q&A session about what's behind her own and Larson-Green's recent emphasis on Microsoft being "principled but not stubborn" about expected coming interface changes with Blue. Among those rumored changes are inclusion of an optional Start Button and boot-to-desktop capability.

Reller said that even though the Windows ecosystem needs to know where Microsoft is going so it can go with the company, the Windows team still needs to listen to its customers and partners about what they want.