Steven Sinofsky, president of Windows and Windows Live Division, is leaving Microsoft effective immediately, reports All Things D.

The move is claimed to be a result of growing discontent within the software giant, with a number of executives reportedly unhappy when working with him due to his failure to be a "team player." Such a move has striking parallels with Scott Forstall's recent exit from Apple.

Sinofsky held his current position since 2009, but he joined Microsoft in 1989, more than 20 years ago. All Things D says responsibility for Windows will now be split between two of Sinofsky's reports: Julie Larson-Green, who will head up Windows engineering, and Tami Reller, who will take care of the business side.

In a press release, CEO Steve Ballmer said the company needed to be more aligned and integrated, with more regular software releases:

I am grateful for the many years of work that Steven has contributed to the company. The products and services we have delivered to the market in the past few months mark the launch of a new era at Microsoft. We've built an incredible foundation with new releases of Microsoft Office, Windows 8, Windows Phone 8, Microsoft Surface, Windows Server 2012, and Halo 4, and great integration of services such as Bing, Skype, and Xbox across all our products. To continue this success it is imperative that we continue to drive alignment across all Microsoft teams, and have more integrated and rapid development cycles for our offerings.

In his statement, Sinofsky wrote:

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.

Update: Microsoft has confirmed the new roles of Larson-Green and Reller in a press release.

From the Verge, we have the text of Ballmer's internal mail announcing the changes:

Over the past few months we have delivered the foundation for a new era for Microsoft. From Office to Bing to Windows Phone and Windows Azure, to Xbox and of course Windows and Surface and everything in between, we’ve unleashed a huge wave of devices and services that people and businesses love. I simply couldn’t be more proud of the effort you have all put in to get us here and to set the foundation for our future. At the Windows launch in New York, at the Windows Phone event in San Francisco, and again at the Build event on Redmond campus, I was struck that while externally many people look at these events as the finish line, they really represent the starting line of a new era. As we enter this new era, and with the successful launch of Windows 8 and Surface behind us, Steven Sinofsky has decided to leave the company. Steven joined Microsoft in 1989 as a software development engineer and has contributed to the company in many ways from his work as a technical advisor to Bill Gates, to leading the evolution of the Microsoft Office business, to his direction and successful leadership of Windows and Windows Live as well as Surface. I am grateful for the work that Steven has delivered in his time at our company. Effective immediately, Julie Larson-Green will lead Windows engineering. She will be responsible for all product development for Windows and Windows Live, in addition to Surface. Julie has been a stalwart leader of building compelling “experiences” from her time on Internet Explorer, through the evolution of Office and most recently to the re-imagination of Windows. Her unique product and innovation perspective and proven ability to effectively collaborate and drive a cross company agenda will serve us well as she takes on this new leadership role. All of the current Windows engineering teams will report into Julie, and Julie will report to me. Tami Reller will lead business and marketing strategy for Windows including Surface and partner devices. She will provide broad stewardship to our PC marketing efforts while managing the line business functions for Windows. Her work on Windows since 2007 has been exemplary and her strong talents in working with internal groups and partners will also serve us well. Tami also will report to me. We are facing a time of great opportunity. What we have accomplished over the past few years is nothing short of amazing, and I know we have more amazing in us. I am excited about our people, I am energized by our ability to change and grow, and I look forward to the success which lies ahead. Thank you for all you do, and please join me in congratulating our new leadership and celebrating all that we have accomplished so far. Steve

And from Paul Thurrott we have Sinofsky's mail announcing his departure: