Windows 8 Release Preview (Pro), Windows 8 Release Preview with Media Center (ProWMC) and Windows 8 Enterprise (VL).
Microsoft has already announced that the Windows 8 Release Preview will be launched sometime in the first week of June. The company has yet to give a specific launch date. Two big tech oriented trade shows are happening that particular week; Computex in Taipei and E3 in Los Angeles. Microsoft could announce the official launch of the Release Preview at either one or both events.
Another leaked list of Windows 8 version numbers by Winunleaked.tk claims that Microsoft is already working on the final manufacturing version of Windows 8, with the version number of 8411.