Another build of Windows 8.1 update 1 has leaked but this time, it’s the MSU that is available for download which makes this leak, a bit harder to install.
The build is 9600.16610 and the MSU leak requires you to perform an update to an existing, fresh RTM install with all applicable updates applied.
In short, you can’t download an .iso and install this leak and you'll need to jump through a few hoops to correctly install the build.
As we had previously reported, there aren't a lot of new features inside the build but we know that enthusiasts will install this leaked build anyway. The update includes the ability to pin apps to your taskbar, access bars on the top of modern apps, IE11 enterprise mode and a few other tidbits here and there.
The update 1 for Windows 8.1 is not intended to be a major upgrade for the platform but it does look like there will be many enhancements baked in that should make using the modern environment a bit more mouse and keyboard friendly.
As with any leaked build of Windows, install at your own risk as the OS could be unstable and do non-repairable harm to your machine.