Just saw on Whedonesque that you can now download a good number of TV shows legally through Bittorrent. They're charging the same amount as iTunes ($1.99/episode). They also have movies available to "rent" (you have to watch them within a certain amount of time after download) as well as games and music. I can't speak to quality or download speeds (Bittorrent is peer-to-peer, so it seems like you might have problems downloading less popular titles), but it's definitely a step in the right direction.
EDIT: Just read elsewhere that these files are only playable in WMP 11, and that it's practically impossible to make backups in case of computers crashing. Not so much a step in the right direction. Somehow there has to be a middle ground between the content producers' copyright control and fair use on the part of the consumer. This doesn't seem to be it.