If McCain wins California, he doesn't need it -- the election is a blowout. Yes, there's a 12% chance McCain win California, but if he wins California, he'll also win Pennsylvania, Michigan etc. Because the correlation is high, I'm not sure taking 12% of 55 ev's is very meaningful.
Taking 12% of California's 55 EV's is the basic calculation, but the probability of winning is based on calculating the S-curve over 20,000 random simulations and seeing where the 270-point is. If McCain wins California, that will raise his probability of winning, but he will only win California 12% of the time in the simulations.
-PJ