Dorothy is played by Alicia Keys (further review has brought us to our senses.)
Andre3000 is The Scarecrow ('nuff said)
Bernie Mac plays the The Cowardly Lion
Don Cheadle plays The Tin Man (I don't know if he can sing, but this is the one role, outside of The Wiz that requires serious acting chops)
(hold onto your crowns, here comes the stunt casting:)
Halle Berry as the Wicked Witch of the West
Queen Latifah as Good Witch Glenda
and finally The Wiz:
Mr George Clinton
I propose this now so it can be released in time with the 30th anniversary of the stinky original...okay America let's make it happen!