Apologies if this has been discussed already.
I had the thought a while back that the KERS system could perhaps be used as an aid for braking stability/traction. In a situation where the rear wheels spun due to too much throttle it could perhaps be automatically activated to 'charge' the unit and absorb some of the power from the engine, or activated in pulses during 'over enthusiastic' breaking, ABS style, to try to avoid locking the rear wheels (obviously the standard brakes would still be on, but in theory it would help to modulate the force a bit).
I had a look myself and couldn’t find anything in the regs that would disallow it, I know there are sections on how quickly power can be 'recovered' but if set up correctly a little help is better than no help. The KERS ECU isn’t FIA controlled so there shouldn’t be much problem from that end.
I expect somebody to pull some reg out from somewhere that contradicts this, but I've been thinking about this since KERS was first announced and haven’t yet read anything concrete.
Cheers