The Windows 8.1 RTM version will be available to OME manufacturers this month, as its development is nearing completion. It is reported that the latest version of Windows 8.1 is Build 9472, which was compiled on July 29, just a few days ago.
Although we have not yet seen the latest version of Windows 8.1, it is certain that there won't be significant changes between the RTM version and the currently released Windows 8.1 Preview. Bug fixes and app updates are the main changes between the Windows 8.1 Preview and the RTM version. For instance, apps like Mail and People will feature a completely new user interface with several added functionalities.
Oh, I almost forgot an important point: the specific version number for this build is 9472.0.winmain.130729-1720.
Since the release of the Windows 8.1 Preview, Microsoft has compiled 41 versions, and it is expected that the final Windows 8.1 RTM version will be Build 9600.