Science is working on it:
Basically, the [University of Washington researchers'] proposal is to spin ultra-thin female condoms woven out of cloth-like fibers and medicine. Above, you can see a magnified image of the resulting condom, complete with sperm who have tried to smash their way through it and failed miserably. The condoms can be woven out of medicines that prevent HIV infections, providing protection against disease while also stopping sperm in their tracks. The electrospun condoms can be designed to dissolve within minutes, or over a period of several days. Women can discreetly put them on before a sexual encounter — either directly, or on a diaphragm or ring — and protect against pregnancy, HIV, and potentially other sexually transmitted diseases as well.
The Bill and Melinda Gates Foundation just gave researchers a $1 million grant to develop the technology.