It's Labor Day Weekend, and the traditional dividing line between summer and fall. The days become just a little bit shorter, vacationers return to their jobs, and the kids return to school. For those who are parents, your thoughts may be turning to the question of annual vaccinations. And even for those of us who are not parents, the recent introduction of the HPV vaccine has made quite a splash - over the past few months, advertisements have been popping up everywhere, telling us about our risk of getting cervical cancer from this previously little-mentioned STD.