Microsoft advised it’s OEM reseller channel of the recently announced dates for Windows 8.1 to start hitting Windows Update. The contents of the message are as follows…

Dear Microsoft OEM Reseller,

Windows 8.1 will begin rolling out worldwide as a free update for consumers on Windows 8 through the Windows Store 12:00 A.M on October 18 in New Zealand (that’s 4:00 A.M October 17 in Redmond). Windows 8.1 will also be available at retail on October 18. So mark your calendars!
If you haven’t already, you can give many of the new features and improvements in Windows 8.1 a try with the Windows 8.1 Preview. Business customers can begin testing Windows 8.1 for deployment in their environments with the Windows 8.1 Enterprise Preview.
Windows 8.1 Commercial OEM (COEM) product will be included on September 1, 2013 price lists for OEM Distributors so that you can begin to place orders in advance of the General Availability (GA) date. OEM Distributors will be allowed to ship their Windows 8.1 inventory to system builders and resellers as soon as they receive it, which may or may not be prior to the October 18 GA date. Please contact your distributor for pricing and availability. In addition, Windows 8.1 marketing assets will be available for use in early October and will be posted on the Microsoft OEM Partner Center.
For the latest Windows 8.1 disclosures, please visit (and subscribe to) the Microsoft Windows Blog.