People don't seem to understand what the GPL covers in term of "derivative" work. If you fulfill an API, that is not covered under the GPL. If you take parts of the linux kernel, modify them and then repackage them, that does constitute derivative work. It just happens that most kernal modules distrubuted with Linux distros are GPLed, but they don't have to be. The module can be 100% new code, and the author can then release it under whatever Liscence they want.