Microsoft has announced that Windows 8.1, aka Blue, will be a free upgrade for all Windows 8 users. Microsoft has also confirmed that it intends to release a public preview of Windows 8.1 on June 26, the first day of the Build developer conference -- and if everything goes to plan, you should be able to get your hands on Windows 8.1 sometime in the fall (it should release to manufacturing in August). As expected, there's also a Windows 8.1 update for Windows RT.