It looks a lot like the Windows 7 and Windows 8 release calendars are following the same timeline. An RTM version will be ready by the end of July.
Microsoft hasn’t waited for the first week of June – as initially announced – to put their Windows 8 Release Preview online. This is an almost final version of the operating system which was made available on the 31st of May.
The next development step will traditionally be the RTM version, or Release to Manufacturing. With the RTM, Microsoft will release the final code for the OS to PC manufacturers so that they can start to create their own images and preinstall Window s8 on new computers.
With the Windows 8 Release Preview, Microsoft has indicated an RTM would come in about two months. This means that an RTM should become available in late July or early August, with Microsoft pointing out that it will continue to have "comments and feedback for Windows 8 and Windows RT" (Windows 8 for ARM).
Another clue given by Microsoft, if everything works as expected, is that "we will be on the right track to provide a common objective: offering PC’s with Windows 8 and Windows RT for holidays".
It would appear that the commercial release of Windows 8 will be in time for the end of year period. This is a similar calendar to that used by Windows 7 in 2009, with the general public release taking place in October. Such a release date will work a lot better than that seen with Windows Vista, which was surprisingly released to the general public in late January 2007.
Like with Windows 7, companies with volume license contracts should be able to get a copy of Windows 8 from the summer. The question is whether they will want to migrate, as it would appear at this stage they may want to wait before making any decision.