Microsoft has just announced that the next version of Windows will be called Windows 7 on the Windows Vista Blog.  The next version of Windows will be the seventh major release.

Mike Nash on the Windows Vista Blog wrote, since we began development of the next version of the Windows client operating system we have been referring to it by a codename, "Windows 7."  But now is a good time to announce that we've decided to officially call the next version of Windows, "Windows 7."

The decision to use the name Windows 7 is about simplicity. Over the years, we have taken different approaches to naming Windows.  We've used version numbers like Windows 3.11, or dates like Windows 98, or "aspirational" monikers like Windows XP or Windows Vista.  And since we do not ship new versions of Windows every year, using a date did not make sense.  Likewise, coming up with an all-new "aspirational" name does not do justice to what we are trying to achieve, which is to stay firmly rooted in our aspirations for Windows Vista, while evolving and refining the substantial investments in platform technology in Windows Vista into the next generation of Windows.

Simply put, this is the seventh release of Windows, so therefore "Windows 7" just makes sense.

Source: Windows Vista Blog