We've heard before that Apple may be working on a service for iTunes called "Replay," sort of a Netflix Watch Instantly-style service that lets you download and stream any movies or TV shows that you've purchased from iTunes. Obviously, with the iCloud infrastructure in place (and iTunes Match already announced and on the way out), it's not too big a stretch to see that actually happening.
But if such a deal is underway, the latest reports say it won't be available for a while. CNET says it has been poking around film studios about such a deal, and at least six differe