A University of Alabama - Birmingham researcher found a significant drop in abnormal Pap results after women were given GARDASIL. From the article:

In testing GARDASIL reduced abnormal Pap test results by 43 percent compared to women not given the vaccine. The 43 percent reduction was for tests that found pre-cancerous changes called high-grade squamous intraepithelial lesions (HSIL) more than three years after women were given the vaccine…While the findings are not definitive that GARDASIL prevents cancer, they do signal the vaccine will spare thousands of women a diagnosis of cell abnormality or malignant changes that may lead to more tests and possibly surgery, said Warner Huh, M.D., associate professor in the UAB Division of Gynecologic Oncology and the doctor chosen to present the data.

So not only is there the obvious health/human rights argument as Amanda Barone has previously argued, but the relatively cheap vaccine also reduces overall health care expenditure by reducing the number of expensive tests and surgeries.