KERS/diffusors etc.

As far as I can ascertain, the following cars will have KERS this weekend.
Ferrari (just Massa on Friday, then possibly both or neither)
BMW (both drivers, at least on Friday, possibly just Heidfeld for the race)
Renault (assessing on Friday, but probably, see above link)
McLaren (definitely, see above link).

Piquet will join Alonso, in having the latest Renault aero-updates and fancies his chances. However, there are rumours that Bruno Senna is being lined up to replace him.

Meanwhile, only Force India have brought in any significant upgrades (more are expected for Barcelona in a fortnight's time).