Although there are also movies from HD DVD studios appearing on Blu-ray, owners of those players aren't quite as excited about the prospect. That's because unlike HD DVD, Blu-ray uses region coding. Region coding was already one of DVD's most contreversial features, as it's designed to control access to content by designating a particular area of the world where a disc can be played. Even though a North American Blu-ray player and HDTV are perfectly capable of reading and displaying the content, all players respect the region coding, effectively making coasters of foreign Blu-ray releases.
The idea of DRM as a trade constraint is becoming a major issue for many people. As the global economy expands to the point where it's trivial to ignore international borders when shopping online, many consumers are frustrated when this freedom is curtailed to prop up an outdated business model. It's even become the focus of lawsuits, such as those Apple is facing over the DRM in songs purchased from iTunes.
Source: Wall Street Journal