David Wallace, a leading figure in philosophy of physics who is currently Professor of Philosophy at the University of Southern California, has accepted the Mellon Chair at the University of Pittsburgh, with appointments in History & Philosophy of Science and in Philosophy.  This should move Pitt into the very top ranks for philosophy of physics (along with Oxford and Michigan).   It's also the second senior loss for USC this year. I expect USC is still likely to remain in the overall U.S. top ten despite these losses.