Is the KERS ouput controlled by the McLaren SECU or can the teams use their own control unit for it? If they're able to use their own control unit, is there much potential for electronically modulating power under launch with it? Thinking of the Renault fast starts and Boullier's comments.

On initial start KERS added to modulated IC reduced power through the conventional clutch is a liability. The ic power is already way below what is available and adding more simply makes it more difficult to avoid wheel spin and uses up KERS energy for no result.

KERS as it is applied to the powertrain currently can only be effectively applied when vehicle inertia is established and wheelspin is not a consideration.
Control of KERS using FIA spec control systems to ensure how much energy is harvested and used negates much of KERS potential and maintains the illusion of a 'boost' button.

Future KERS systems, if they are to be relevent to road vehicle developments and energy saving/CO2 reduction, must be applied as part of the over all power available and be closer intigrated to the powertrain.

My teory.
The good starts for Renault is down to the exhaust layout. it makes the underside work better at a lower speeds.

It denies more oncoming air to go under the car than the traditional layout can "suck" away at low speed -> Renault got good chances to be first and second at Monaco GP

I dont think that the Renault or any other car gains anything from initial start from its exhaust or undertray aero.
I have considered that Renault use their front exhaust outlet rather more for a form of mass exhaust gas virual side skirts, than for increasing the rear diffuser effect.
At least on acceleration and high speed strait line speed situations where this would result in better streamlining and smoother over all air flow.
This could account for the Renaults high top speed.
I am not sure what they do when downforce is needed.
Perhaps the exhaust goes elsewhere?
On recent results, I would go more for the Mercedese at Monaco due to its shorter wheebase.
DRS will not be of much use at Monaco, KERS could be the winning thing there.

After watching the vid of the BBC Qualifier and a replay of the start last week, it seems to be going good and better than the others when it comes up to high speed or mid speed.. so i have to believe you on the vortex doing something good on high speed aero.

But i still think the exhaust is also blocking the oncoming air. hence the oversteery behaviour it seems to have. (my impression with nick heidfeld)

I would guess that the oversteering was more as a secondary result of not working the front tyres in balance to the rears.
There are far to many variables and compromises to make a positive guess though.

Does anyone know how red bull are getting on with sorting their KERS?