One reason I was so disgusted when Kindle debuted with its super proprietary Mobipocket format was because of the history of companies, both big and small, to stop supporting the proprietary format of the month, leaving its consumers high and dry.
Wal-mart has announced that it will end its video download service after just one year of being open. Users who have downloaded movies through this service can continue to watch them on the device that contains the downloaded movie and the necessary software to view the movie. Because of DRM, though, it means that the movie cannot be transferred or viewed on any other device. So if the harddrive crashes on the unit that contains the movie or you choose to upgrade, the movie is lost forever.