Sky Player is not entirely free on the PC. There are only a select few programs that can be watched for free and you need to be subscribed to the TV counterpart for it to work. So for example to watch Sky Sports 1 Live, you need to subscribe to Sky Sports 1 and then be subscribed to either Sky Broadband Unlimited/ Sky Multiroom / Sky Player Multiroom.
I have no doubt, in fact ill bet that Sky will charge for the 360 use with some stupid new sub called "360 multi-room" or something. They are in it for the money and always have been from the start. Sky never, ever, give anything away for free.