At least they are taking advantage of the step.
Some guesses, It may be the intake to cool the KERS batteries, if they did some MAJOR repackaging of their unit. They still had a decent amount of trouble with it last year, and that step gives them an excuse to put an intake there. Or it could just be a little spoiler. There isn't usually a whole lot of room to work in the nose of the car though with all the suspension and fluid housing there.