Last week rumours that Don Mattrick was leaving Microsoft for Zynga were confirmed. Today, Steve Ballmer announced Mattrick's replacement: Julie Larson-Green. She will officially be in charge of the 'Devices and Studios Engineering Group', which includes Microsoft's gaming division.
Larson-Green has been at Microsoft for 20 years and headed up design for Microsoft Office XP, 2003, and 2007, as well as Windows 7, Windows 8, and Windows 8.1, amongst other projects, so she certainly brings a lot of experience to the role. Indeed, she is tipped as a future successor to Ballmer as Microsoft CEO.
Microsoft stock is reportedly up since the announcement.