As I said, this is a huge battle won (but, of course, the war will never be over), since the tiny R4 chip was the most popular pirating device on DS and a true nightmare for developers. It still remains to be seen how will this affect the industry in the future: even though now illegal in Japan, the chip could probably still be produced and sold illegally. Are people willing to take such risks? Possibly, but the numbers will certainly fall. So it can be considered an important win against the pirates.
Thanks Kotaku for the heads up.