Seems Sky has an interest in the PS3. Personally, I think we may see something similar to Nexflix, some timed exclusivity on the 360, then it makes its way to PS3.

http://www.ps3news.com/PlayStation-3/sky-player-and-skytv-service-may-be-coming-to-playstation-3/

that would be amazing.

The thing I want to know is how is Sky broadcasted on 360.If through the internet,then wouldn't it be neceassary for ever 360 to have atleast an 8mbps connection to play HD Sky channels.Now do the 360 customer play extra for this service or is free.

so PSN is like xbox live and it is free ?

Just 1 year behind for most features as Sony add them on to add parity again.  Can't see this happening anytime soon, also Microsoft do have their streaming tech to dangle like a carrot to Sky for future HD content to try and tie some exclusivity down.  Given my short experience with the service so far though it's amazing and I can see why Sony would push to get the feature.

does a 360 user have to extra or is it covered in its yearly xbox live subscription

Hard to summarise in a paragraph or two but the following link is great for answering questions:

http://www.avforums.com/forums/xbox-360/1110404-sky-player-launching-28-october-2009-faq.html

Basically if you have Sky already then it's free for On Demand stuff, if not then it's extra.