I'm sort of disturbed by the the title of the piece on NewsForge, A GPL requirement could have a chilling effect on derivative distros. It gives one the impression that this is some new thing. I remember reading this in the GPL years ago, and the fact that MEPIS, etc. have chosen not to provide the source code doesn't negate the legality of the document.

It's a license, people, created to protect rights. This clause in the GPL is important for making sure that the cost of sharing is distributed appropriately. Consider the following example. Project X is an open source software application which is extremely popular and maintained by a small community of developers. These developers not only volunteer their time, but their personal funds to provide the bandwidth for everyone to download the binaries and the source code for their project.

Now Project Y comes along and repackages and adds on to Project X's software without modifying the original source code, like MEPIS in the article. But instead of supplying the source code on their site, they point users to Project X's source code download. When Project Y becomes popular, now the developers on Project X are faced with supporting source code downloads for Project X and Project Y.