On my GTX465, WUs are still finishing in the range 480~520 sec, as they have since Rytis broke the Fermi barrier. (I recently up-clocked the GPU slightly, so they are now at the lower end of that range.) I confirm that the GPU is running at an astonishing 98%.
What I have noticed is that the more recent 514nnn & 515nnn series WUs are downloading with ETC estimates that are much higher, in the neighborhood of 1.5 hrs oo) But they are still finishing in the same ~8.5 min. Go figure.