Here's something I bet most people don't know... Apple gets its source material from a much higher quality source than Blu Ray which is why their 720p iTunes content looks so good.
As far as I know Apple don't encode the content, the movie / TV Studio encode the content and send them to Apple to sell. This means that both the Blu-ray version and the Apple versions are more than likely encoded from exactly the same master source.
TV has pretty good horses inside for doing the hard work of 1080p files: decoding.