Windows 8 [Information from wiki]

A roadmap timeline slide shown by Microsoft at the 2009 Professional Developers Conference shows that Code Name "Windows 8" is scheduled to be released sometime around 2012. Development and other aspects of Windows 8 have not been detailed in public, although job listings have mentioned improved functionality for file access in branch offices.

A recently-departed Microsoft employee's blog has revealed a rough version of Microsoft's roadmap for key software, including Windows 8. According to the information, Microsoft aims for Windows 8 support to start on July 1, 2011. Support for Windows Server 2012 starts on July 2, 2012.