That is what is so exciting / different about this. When you make available software under the GPL, you have now entered into a CONTRACT (not copyright anymore) with all users that binds you to the terms of the GPL and gives them a right to sue for violations of THEIR independent rights.
This is the power of this new ruling, they can then sue you or anyone for breaking this agreement with them. Obviously will take some experience to see how far this can be taken. My understanding is the conservancy may want to try to leverage this to try to get GPLv3 effects into GPLv2 and a few other things the developers of for example Linux are not so hot on.