It's a network that, from what I understand, connects to a user's computer that has the software program that you want, then makes a copy of it and sends it to you, all for free. However, I'm not sure of the legality of it... though there was an article in the newspaper saying that now you can download a program that makes you pay for anything downloaded off of Kazaa, but the good thing about that is that you're paying for copyrighted material, so it's perfectly legal. The rumors about a trojan, I'm not sure about that, though I imagine it would be very easy to create a virus and infect users through such a huge network (in fact, there is currently a virus in Kazaa that affects some Windows users...)
