Brief Legal Update
The largest issues to consider when determining whether or not Apple incorporate Bittorrent file sharing with iTunes are:
1. Can Apple trust that their clients not crack DRMs protecting purchased DVDs?

my response: Probably not. There is already a very strong culture of defeating protection to use your purchased property however you desire. However, if this would be the case with iTunes, it seems like the use of Bittorrent and its copying nature would only further encourage piracy.

2. Can Apple utilize the Bittorrent file sharing model legally?

my response: Probably. Because Apple would hold licensing agreements and be charging for these services, they most likely would not be breaking any copyright laws or licensing agreements as long as they were giving throw backs to the movie companies. On the other hand, once the movies were transferred it would be difficult to control how the customers used their materials.

my sources and case summaries will follow.