Building the next release of Microsoft Windows is an industry-wide effort that Microsoft approaches with a strong sense of responsibility and humility. Windows 8 reimagines Windows for a new generation of computing devices, and will be the very best operating system for hundreds of millions of PCs, new and old, used by well over a billion people globally.
Link – http://blogs.msdn.com/b/b8/archive/2011/08/15/welcome-to-building-windows-8.aspx