Faculty Changes in the Last Year and the Overall Rankings
The summary of faculty changes since the fall 2006 survey has led various students to inquire about how these changes would affect the overall rankings. I'll just comment on the US, since I think I have a better sense of that scene. The first thing to say is that, in almost all cases, far more important than any change in "overall rank" is the way in which senior moves will affect the attractiveness of programs in various specialty areas--so with the senior moves and the tenurings, especially, take note of the areas those faculty work in. (Attend to the junior hirings, too, but as a PhD student, you will want to have a tenured faculty member as a supervisor of your thesis.)
Turning to the overall results, I would expect a new survey, reflecting last year's changes, to have NYU still on top (perhaps by a wider margin), then Rutgers, and then a gap before the Princeton/Pittsburgh/Michigan grouping (with Michigan probably now at the lower end of that cluster). That would be followed by a cluster of Stanford, Harvard, MIT, UCLA, North Carolina, and Columbia. The next cluster (programs ranked 12-15) would be Arizona, Berkeley, Notre Dame, and (a new arrival) Yale--and Yale could well be on the cusp of the next group. The "top 20" would be rounded out (in some order) by Brown, Texas, UC Irvine, UC San Diego, Cornell, Chicago, Southern California, and, maybe, CUNY. Outside the top 20, the biggest upward movement has surely been by Colorado (which ought to be solidly back in the top 30, I should think) and Northwestern (which ought to be solidly back in the top 50, perhaps higher), while UC Davis is at risk of dropping out of the top 40.