The Obama campaign's "Julia" ad repeats the claim.
Romney supports the Blunt Amendment—which would place Julia's health care decisions in the hands of her employer—and repealing health care reform so insurance companies could go back to charging women 50% more than men.The "Julia" presentation tacks on that bit about charging women rates 50 percent higher than those charged to men. That's a number that begs for a fact check while supplying the likely essential context that the higher rates represent risk calculations. The ad hints at gender discrimination, but that's just false if higher rates are justified by gender-related differences in medical costs.
Jeff adds: 5/11/12: Bryan's in-depth takedown of PolitiFact's Julia rating is well worth the read.
Edit: 5/11/12: Removed repeated instances of words "supposedly give" in first paragraph-Jeff