According to a series of benchmarks, out of all Intel powered Macs, the MacBook Pro faired fastest in testing Photoshop CS 2 via Rosetta. What is interesting is that though in Rosetta, the Photoshop CS 2 benchmarks on the MacBook Pro proved faster than its Windows native counterparts in terms of performance when compared.
What this means is that once an Intel native version of Photoshop for OS X is available, performance should be even better considering the lack of any translation/emulation.
In addition to this, GearLog also tested Windows XP performance on all Intel Macs. Though there are very few readily available drivers out for the OS on Mac hardware, benchmarks were impressive.