After releasing Windows 8.1 Update to TechNet and MSDN subscribers on April 2nd, and via Windows Update for the vast majority of Windows 8.1 PCs on April 8th, Microsoft has now released Windows 8.1 Update from its Volume License Service Center.
In a blog post today, Microsoft said that VLSC customers can download Windows Server 2012 R2 Update and Windows Embedded 8.1 Industry Update as well. The blog also says that the version of Windows 8.1 Update from VLSC and MSDN does not have all of the fixes that are available in the version accessible via Windows Update. It states, "Therefore, Windows Update and WSUS will offer the Update again to devices that are deployed by using this media."
There's no word on when this will happen, but when it does, the download will be a small one and won't require the full reinstallation of Windows 8.1 Update.
The blog also mentioned the previous issue that the update currently has with Windows Server Update Services (WSUS) servers; the bug causes the servers to stop scanning against WSUS 3.0 SP2 or WSUS 3.2 servers which are configured to use SSL and have not enabled TLS 1.2. While Microsoft has a couple of workarounds for this problem, there's no word yet on when it will release a patch that fixes the issue.