Rap, along with every other form of music, is a entertainment. Violence has been here since the beginning of time. Violence is everywhere. Why people (i.e. the media) are so quick to link acts of violence with soley with rap music is stupid.
For the people that got gunned down before their time, its a very tragic situation. But to say that the music was the sole cause is outrageous. There's a lot of jealous ppl in the world that don't wanna see the next person make somethin' outta themseleves. Thats life.
I'm sure heavy metal has some instances of violent lyrics, among other things. Why just focus soley on rap music? Each genre has its good/bad aspects. In the end, its all a form of expression and entertainment.