Microsoft started dropping the first Windows 8 references as early as March 2009; yes, long before Windows 7 was finalized. And the next iteration of the Windows client and server operating systems are now taking shape in Redmond. The software giant already confirmed officially that Windows 8 client and Windows 8 Server are being developed in parallel. Just as it was the case for Windows 7 and Windows Server 2008 R2. Still, the company is mute on the evolution of Windows, including features, capabilities, the actual timetable, etc.
The successor of Windows 7 is planned for availability within three years after the GA of its predecessor. Microsoft said it would impose such a rhythm after the release of Windows Vista, promising to never again repeat the gap between Windows XP and the delivery of the OS initially codenamed Longhorn. It took the software giant less than three years after Vista’s general availability to offer Windows 7 to customers around the world, and the same is valid for Windows 8.
Full read: Windows 8 in 2012, Beta as Early as 2011 - Milestone 1 has been reached, reportedly - Softpedia