They said they'd do it by the end of August. And as we head into the last stretch, it seems Microsoft has released to manufacturing (RTMed) Windows 8.1, its next release of Windows.

Windows SuperSite editor Paul Thurrott tweeted on August 23 that Windows 8.1 had RTM'd. Thurrott said the final RTM build number is 9600.16384.130821-1623.
I talked to another contact of mine who said the internal RTM e-mail made the rounds inside the Windows division on August 23. A third source close to the company confirmed Microsoft RTM'd Windows 8.1 on August 23, and announced internally that the quality metrics for Windows 8.1 were back in line with those of Windows 7. (The vast amount of changes in the Windows 8 code base resulted in an increased number of crashes and hangs for Windows 8, one of my contacts explained.)
Windows 8.1 is ready, gets released to manufacturers | Microsoft - CNET News