I've heard from two of my sources in the past week that Microsoft's ship target for Windows 8.1 Update 1 has shifted from March 2014 to April 2014.
The idea remains to use Patch Tuesday to distribute the coming so-called "Spring" update via Windows Update, my sources said. If that is the case, Windows 8.1 Update 1 should be pushed to users on April 8, rather than March 11.
Windows 8.1 Update 1 is a collection of features and fixes for Windows 8.1. Most of the new features are aimed at making Windows 8.1 more palatable to those who prefer using a mouse to navigate the latest Windows release.