Mos Def and Talib Kweli, two whirlwind rhyme-slingers in their own right, first came together as Black Star in 1998. Their first album, Mos Def & Talib Kweli Are Black Star, was propelled by Mos Def's poetic lyrics and Kweli's poignant delivery, and it instantly had heads clamoring for more material from this act, which took its name from a shipping line founded by Pan-Africanist Marcus Garvey. Now, more than a decade later, the duo is back, releasing singles for Black Star Aretha, a tribute album to Aretha Franklin that's the talk of the rap world even without a release date. While individually the two are imposing forces to be reckoned with, together they always bring the ruckus.