Original Director's Cameo
When Shaft goes to Lennox Lounge, he says "hello" to a guy that looks like a black version of Einstein. This is the director of the original Shaft movie, Gordon Parks.
New Director Makes a Cameo
The director of the new movie, John Singleton, shows up in the jail sequence after the fight scene. He is the officer sitting outside the jail cell who doesn't do anything to stop the fight.