[mattchamb]

Also to compete with Cortana on windows phone, which lets you register voice commands to run specific apps and provide it input [1].

[1] http://channel9.msdn.com/Events/Build/2014/2-530 - Integrating Your App into the Windows Phone Speech Experience

[sibbl]

In fact apps can register for voice commands since the release of WP8. Microsoft just improved it so you don't have to register e.g. 1000 movie names to enable the WP voice recognition to understand them, but telling WP to listen for a movie name.