Looks like the rumor mill was right. Windows 9 will finally be unveiled to the public on September 30 at a press event.

Not only will Microsoft highlight the new features in the next version of Windows codenamed "Threshold" โ€” virtual desktops! Cortana! A new Start menu! No more Charms! โ€” it will also release a technical preview of the operating system that anyone can try out. [The Verge]