California is a very progressive state, and it sort of surprises me that someone would alienate that voting base. Whitman believes marriage to be between a man and a woman, and is a supporter of the law which made gay marriage illegal in California.
In August, Judge Walker Vaughn struck down Prop 8 in a ruling. The law is still going through the appeals process- but for the time being California joins the ranks of states where gay marriage is allowed.
The Meg Whitman Jerry Brown debate on Prop 8 was interesting, and you can see their arguments in the video below.