The late Tupac Shakur was probably the most mercurial rap artist who ever lived. One minute he was rapping about the good life, the next about altercation; only occasionally would the true warrior poet in Shakur emerge, the street philosopher who explored his links to traditions raging from jazz scatting to the wandering ballad of the blues traveler. Such a blissful moment occurs toward the end of "Life Is a Traffic Jam," a song written specifically as a performance piece for Eight Mile Road, the band Tupac's character belongs to in the film. After a laughable performance by the horribly pretentious Thandie Newton, Shakur injects the track with a sense of revelation. Tupac Shakur, jazz poet? One listen to his incredibly agile sashay around the driving upright bass line could make a believer out of even hard-core rap foe C. Dolores Tucker.