This New York Times article proposes that circumcision prevents AIDS.  Of course, things are not so simple.

We agree on one point:  the spread of HIV (and other STDs for that matter) in uncicrumcised men is less than those in circumcised men.

But Tina Rosenberg's article misses the important point:  one has to get a disease in order to spread it.  So while I might agree that in some contexts – circumcision is (way) better than nothing – it is neither a vaccine, nor a good argument for universal circumcision.