"Hey Cortana" comes to rival "OK Google" in new video
Spanish Microsoft blogging site MSFTPlace has captured a video showing off the new 'Hey Cortana' feature that will be available in the forthcoming Denim update for Windows Phone 8.1
Note: This feature will only be available on newer Lumia hardware capable of passive-voice activation (Lumia 830, 1520, etc). The HTC One (M8) should be able to perform this function, but will require a firmware update by HTC to enable it.
Click on over to MSFTPlace for more details of how they ran Cortana through her paces.