As developers evaluate Apple's Mac OS X 10.7 Lion Developer Preview, Microsoft has a beta of a new OS referred to as "Windows 8" and will unveil it this September and ship it in 2012, according to rumors. Conjecture about features and purportedly leaked screenshots abound, including shots of a Windows App Store, at a Chinese site called cnBeta. Microsoft has not commented on the rumors.

Analysts expect Windows 8 to either run on tablet hardware and PCs, or be available in two versions. CNN Money quoted an analyst saying that Microsoft is "two generations behind Apple and Google" in developing a tablet OS. A Windows Phone 8 is also rumored to be part of Microsoft's plan, with apps that can run on phones and tablets, and possibly PCs.

The WithinWindows blog posted supposedly leaked screen shots of features, and eWeek described possible features, including an Office-like ribbon in Windows Explorer and some Windows Phone 7 features ported to PCs.

The San Francisco Chronicle reported that Microsoft will unveil the news at a Microsoft Professional Developers' Conference, which Microsoft announced it would hold from September 13 through 16 in Anaheim, California.