The end goal appears to be good news for consumers.
"We will strive for a single experience for everything in a person's life that matters," Ballmer wrote. "One experience, one company, one set of learnings, one set of apps, and one personal library of entertainment, photos and information everywhere. One store for everything. Microsoft has the clear opportunity to offer consumers a unified experience across all aspects of their life, whether the screen is a small wearable, a phone, a tablet, an 85-inch display or other screens and devices we have not yet even imagined."
Here are the key power players in the new Microsoft structure:
Terry Myerson. As the head of the OS Engineering Group, Myerson will be the cook responsible for ensuring that Microsoft's OS products are cohesive and work together. This likely means that Windows Phone and Windows will move closer together over time.
Rick Rashid, the formerhead of Microsoft Research, will be responsible for "OS innovation" research.
Julie Larson-Green will run the Devices and Studios Engineering Group, responsible for all hardware development (Surface, Xbox) as well as "studios," meaning first-party games, as well.
Qi Lu will lead the Applications and Services Engineering Group, making him responsible for apps in productivity, search, communication, and more. He'll be the face of Office, Skype, and other key Microsoft software.
Tony Bates will lead the Business Development and Evangelism Group, responsible for communicating the changes to Microsoft's partners, and to continue encouraging them to keep developing for the Windows platform.
Other key players will include Eric Rudder, who will lead Microsoft's Advanced Strategy and Research Group, Tami Reller, who will be responsible for all of Microsoft's marketing, and Satya Nadella, who will run the Cloud and Enterprise Engineering Group. Craig Mundie will be running a "special project" for Ballmer.
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