SKY have struck a deal with X-Box in the UK.

[Mistershine]

http://skyplayer.sky.com/aboutskyplayer/online-live-tv.html

This has a list of current skyplayer subs, but it seem to cost the same as normal sky.

There is a demo stream to watch as well.

 

My in-laws have a sky package, so can I use their username and password to watch it on my 360?