acording to Peter van Egmond(a Dutch F1 photographer) who wrote a collumn this month at
www.verstappen.nl Renault's great starts have everything to do with electronics.
Renault apperantly use the transponder in the tarmac to their advantage(the transponder sees the car, BUT: the team can also see the transponder), the driver just has to press the launch button when the first red light goes on, and when the transponder shuts of, the car launches.
Trulli and Button just had to hold that button.............
Peter heard this from someone who works at Renault.