It"s not really a surprise that Microsoft is already at work on the generation of Windows which we will call Windows 9, for now. In a recent change for Microsoft, they have begun using code names that eventually turn into the product that hits retail. For example, the code-name of Windows 7, was Windows 7, same with Windows 8 and as you would expect, the codename for Windows 9 is, you guessed it, Windows 9. Of course, Microsoft will likely refer to the next generation of Windows as Windows.next or Windows vNext too.
MsftKitchen did a bit of digging around Windows 9 and already found the moniker listed on several Microsoft employees profiles and other locations around the web. While we had little doubt that Windows 9 was already in the planning/development stages, Microsoft employees are wasting no time and are wearing Windows 9 as a badge of honor.
What would a good rumor be without conflicting information? Even though Microsoft employees may be referring to the next generation of Windows as Windows 9 or Windows vNext, Win8China is also reporting that development work has kicked off as well. But, this source is saying that Windows 9 is being called Windows Blue, or will have a sub-component by the code-name Windows Blue (translation confusion). Further, the Windows Blue moniker is said to be a new base for the Windows platform too. At this time, it is far to early to speculate if Blue will be the foundation for the next generation of Windows; Win8China expects the first build of the next gen platform to arrive in the near future.
Source: MsftKitchen | Win8China
Thanks for the tip Niekess