There is an interresting initiative going on in France right now involving Matroska. A group of independant movie theatres have decided to sell the movies they are showing as a digital download. You still need to go to the theatre, but for 5€ you can get the movie on your USB key in HD Matroska and play it at home. There is no DRM involved.
This is probably the first case of Matroska movies being sold legally. It is currently an experiment that is spreading in France, we hope it will become a lot more common and we wish all the best to this project.