According to the latest tweet from Graeme Boyd, Europe's Xbox Community Manager, on October 27 you'll be able to watch TV from Sky on your Xbox 360.
Looks like the channel line-up and pricing will be revealed at launch.
Here's the tweet for proof:
October 27 - that's the date when you'll be able to watch TV from Sky on your Xbox 360. Channel line-up and pricing to come at launch
Good thing, that.