The MPAA's "University Toolkit" (a piece of monitoring software that universities are being asked to install on their networks to spy on students' communications) has been taken down, due to copyright violations. The Toolkit is based on the GPL-licensed Xubuntu operating system (a flavor of Linux). The GPL requires anyone who makes a program based on GPL'ed code has to release the source code for their program and license it under the GPL. The MPAA refused multiple requests to provide the sources for their spyware, so an Ubuntu developer sent a DMCA notice to the MPAA's ISP and demanded that the material be taken down as infringing. Link