My first thought on hearing this was, "D'uh! Of *course* it's a form of sex discrimination. But that doesn't actually mean it's a bad -- or even unfair -- thing to do..."
But then perhaps I've been blinded by being in the insurance trade for so long. It's been about fifteen years now, come to think of it...
What d'you think, people? Should it be illegal for insurers to charge women less for car insurance because they cost insurers less?
What about my line of work? Is it a *bad* form of age discrimination to charge an eighty-year-old more for medical insurance than a twenty-year-old?