The modding issue has always been a touchy one. In case you’re not aware of it, there are available for almost every game console or handheld a number of hardware-based hacks that allow one to play pirated games and/or homebrew applications. These range from simple boot discs to soldering extra connectors to your console’s boards to simple flash drive-based frontends that take advantage of security holes in the system. Like P2P software (or, say, a gun), it’s not inherently illegal, but it is an enabler for illegal acts.
The DS’s well-known interface (the GBA cart interface) and extensive feature set have drawn pirates and developers alike. And very early in the handheld’s life, a special cartridge with writable memory (essentially a small flash drive with a GBA cart interface) became available. The types and capabilities soon multiplied, and in this writer’s opinion Nintendo missed the boat on containing this mess. While there is a burgeoning homebrew community for the DS and other consoles, it’s no surprise that more people use it to play pirated ROMs downloaded from the internet. Nintendo has had enough, apparently, and is suing five Japanese firms (unnamed)(R4 among others) associated with piratical behaviors. I could have just told you that in the beginning, but then I wouldn’t have been able to write all those words up there.
Update: Predictably, sales of the R4 Revolution (and others, I assume) have increased by a huge amount. Maybe there’s some insider trading going on here.