Just to let you know, even though i say that Eminem and Jay-z have got the some of the best rap lyric skills out there does not mean I like them. In fact, I hate rap. I am looking more at the music from a critical point of view not a personal point of view.
And I have to agree that rap might not be considered music given the fact that it lacks the element of melody. However, hip hop is expanding and with the small female interludes that are popular in rap "songs" (a shocking paradox), the void in the melody department seems to be fulfilled, though somewhat horribly.
I know people will cringe at this thought, but rap is more closely related to poetry than it is to music. Well, I guess it's just the state of the world that has somehow allowed for this form of art to barge into the music department.