RMS on GPL and Plug-ins

Andy Tai writes "RMS has written an article explaining how the GPL is applied in programs using plug-ins like Photoshop or the GIMP. His article can be found here " Apparently it is illegal to write a GPLd plug-in to a non GPLd program if they link in the same code (or am I really misunderstanding this?). Update Andy wrote back saying that Gimp plug-ins etc don't count 'cut they are seperate executables. If someone has a few examples of what plug-ins would theoretically apply here, send them my way.