I'm very sorry, but there's nothing about the demos shown of XB1 Kinect that makes it a 'conversational voice-control.'
Xbox, play Ryse, Xbox On, Xbox watch CNN, Xbox Share, Xbox Volume Up.
All these are 'navigational', as their cues to activate a distinct aspect of a programming feature that is baked into Xbox. Conversational means it understands context, whereas all Xbox is doing is catching for specific strings of your voice to active a specific string of command.
You can argue that Xbox's range of control is wider and richer, given that they've set-up more hooks linked to more voice-options (Bing, etc), but what Xbox is doing is not that different from what Google TV has been doing, or what other Smart TVs with all their similar voice/navigation gimmicks are doing.