Well, we didn’t see this one coming: Microsoft Windows head Steven Sinofsky is leaving the company, effective immediately, the company announced today.

In his stead, Microsoft is appointing Julie Larson-Green, who led program management for Windows 7 and Windows 8, as head of Windows software and hardware engineering. Microsoft chief financial officer and chief marketing officer Tami Reller, who’s now one very busy lady, will take over the business side of Windows. Both will report to Microsoft chief executive Steve Ballmer.

“It is impossible to count the blessings I have received over my years at Microsoft. I am humbled by the professionalism and generosity of everyone I have had the good fortune to work with at this awesome company,” Sinofsky said in a statement today.

The news was first reported by All Things Digital several minutes before Microsoft released its official announcement.

Sinofsky was Microsoft’s front-man for both Windows 8 and its Surface tablet, and his departure comes as a shock given that the launches for both products have gone off without a hitch. With Windows 8, he had the almost impossible task of convincing us that Microsoft has finally figured out a way to make Windows work on tablets, and he had an even bigger challenge pushing Surface tablet, Microsoft’s first computer.

“I am grateful for the many years of work that Steven has contributed to the company,” Microsoft said in a statement. “The products and services we have delivered to the market in the past few months mark the launch of a new era at Microsoft…”

Not surprisingly, Microsoft’s announcement makes it seem like Sinofsky’s departure was mutual. But AllThingsD reports that there was also growing conflict between Sinofsky and other Microsoft executives. (If this story sounds familiar, it’s because Apple’s iOS head Scott Forstall got booted for practically the same reason.)

Update: Owen Thomas over at Business Insider reports on another possible reason for Sinofsky’s move: He wanted Steve Ballmer’s job. As someone who knew the ins and outs of managing both Office and Windows, Sinofsky was long thought of as a potential candidate to replace Ballmer as CEO.


Above: Julie Larson-Green

Image Credit: Sean Ludwig

But just because Sinofsky is out, it doesn’t mean that Microsoft’s grand plan with Windows 8 is slowing down. After the Windows Vista debacle, Larson-Green was the one who pushed the Windows team to work together. She was one of the big reasons Windows 7 ended up being such a solid operating system (when last have you heard anyone complain about it?). She had an even bigger role with Windows 8 and its sibling, Windows RT, as head of the Windows program.

VentureBeat’s Sean Ludwig and I had a chance to chat with Larson-Green at Microsoft’s Windows 8 launch event in NYC (after Sinofsky ran away from our camera). Check out our interview, where she wasn’t afraid of bringing up the controversy around Windows 8’s new interface, below.

Photo: James Pikover/VentureBeat

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