According to an article on the MyCE (My Consumer Electronics) Website, the RIAA ( Recording Industry Association of America) and the MPAA (Motion Picture Association of America) have recruited Mastercard to "govern" the Internet.
According to the article, Mastercard will in essence stop payments made to websites who the RIAA and MPAA claim to violate their copyrights. While technically this can all be done according to the law, it seems to be a big issue of anti-trust and at least violation of due process.