Windows 8 was launched with a developer preview last year, followed by the currently available Consumer Preview. The next release of Windows 8 has just been announced through the Building Windows 8 twitter account.
At a developer event in Japan, Steven Sinofsky made the announcement that Windows 8 Release Preview will be released in the first week of June 2012. Expect another extensive blog post on the Building Windows blog soon detailing what’s changed in the release.