For anyone (like me) who hadn't heard of the change regarding the rear brakes in the article Fenderman posted hear is a quote from an autosport article:
Basically I think that, because the energy recovery systems are going to be wreaking havoc with the rear brakes, the regulations allow some electrical system to ensure that a certain amount of force on the brake pedal always corresponds to the same amount of braking force on the car.
ARTICLE 11.7: REAR BRAKE CONTROL
As part of the new powertrain regulations, a large part of the cars' power will be provided by energy recovery systems.
What was termed KERS is now ERS-K and has effectively double the power output, for five times longer, than current systems.
Harvesting this much energy under braking will affect the braking effect at the rear wheels, so an electronic rear brake control system will be allowed.
This will be used to offset the ERS-K effect by aiding the braking effort at the rear, negating the need for the driver to constantly alter the brake bias.
Basically I think that, because the energy recovery systems are going to be wreaking havoc with the rear brakes, the regulations allow some electrical system to ensure that a certain amount of force on the brake pedal always corresponds to the same amount of braking force on the car.