As the title says really. Neither company has obliged in releasing any useful information about this other than a statement by Bill Gates in his CES Keynote that it is happening at some point.
Presumably, the service available will be
BT Vision, which is already available to BT customers though an additional set-top box, giving all the freeview channels plus various TV on Demand services. They also have an downloadable movie shop.
The service charges a one off connection fee, and uses individual charges of a few pounds per piece for On Demand content, which are paid through the normal BT bill.
It will be very interesting to see how this supplements/replaces Xbox Live Video Marketplace in the UK, and if BT will be rolling this out in other countries as well. It would certainly be to their advantage, as they've got some pretty big media companies supporting BT Vision.
BT And Microsoft To Bring IPTV To The Xbox 360 
