Google Hangouts work on PCs, laptops, and phones. When I get a hangout call, it rings on all devices where I'm currently logged into hangouts.
TV is the only place Xbox wins today. Though google does have some TV toys right now (Google TV and Chromecast). They could probably look into adding a webcam to that with hangouts.
Imagine having a group call on Xbox One - TV, that would be a sweet conversation and I for one really appreciate this new feature.