Wow, this article was never investigated beyond the inquiry of some FBI agent:
The Internet's Wilder Side, according to the New York Times
Why do I say that? Well, check out that art, for one. It does *mention* that "many" of the 500,000 IRC users are just there to chat, but most of the article is about how IRC is where evil hax0rzing happens.
Good lord. I use IRC to keep in touch with friends of mine who used to be local, but often are now spread out over great distances. I've also met more local people through it. I've also frequently used it for business (NOT haxzorzing!) purposes, even now I sit on the IMC channel to find out what's going on there.
Oh wait, I guess that last one proves I'm a pirate evildoer. YARRRR!