The AAAS has a nice site that lists U.S. programs in science and engineering public policy (SEPP) and provides a guide to what prospective students should look for. The faculty at these universities also do research in the field, of course.
Science Magazine has a similar article posted on careers in S&T policy, which also lists U.S. programs and a few in Europe, Canada, and Japan. It also lists some places where an S&T policy wonk might find work, i.e. mostly the S&T policy organizations of governments. These lists are not comprehensive, though. One (maybe this one) could easily add to them.
R. D. Shelton