Microsoft President Steven Sinofsky made the announcement during an on-stage appearance at Japan's Windows 8 Dev Days and more broadly on the Build Windows 8 Twitter feed.
The beta version of Windows 8 came out on February 29.
The release preview is the last stage before a product's final version.
The final version of Windows 8 will launch this October according to a recent report.
Windows 8 is intended to unify Microsoft's flagship OS on the desktop and tablet. Windows 8 is tooled to run on on ARM chips as well as so-called x86 chips that power traditional PCs.
For those who intend to get a new laptop, you can just wait until Windows 8 is officially released end of 2012.