This is what I found.
Just found this. @4:40 PM August 2014 update rollup for Windows RT 8.1, Windows 8.1, and Windows Server 2012 R2
This is what I found that it does. Looks like it mostly not for desktops.
Install this update to resolve issues in Windows. Precision touchpad improvements ? three new end-user settings have been added: Leave touch pad on when a mouse is connected; allow right-clicks on the touchpad; double-tap and drag.? Miracast Receive ? exposes a set of Wi-Fi direct APIs for Independent Vendor
(IHV) drivers or OEM drivers to develop Windows 32-bit applications that run on all supported x86-based or x64-based versions of Windows 8.1, enabling the as a Miracast receiver.? Minimizing login for SharePoint Online ? reduces the number of prompts with federated use in accessing SharePoint Online sites. If you select the ?Keep me signed in? check box when you log on for the first time, you will not see prompts for successive access to that SharePoint Online site.Windows 8.1 update is not mandatory, but everyone running Windows 8.1 is strongly recommended to install it as soon as possible.