While the new Mac Pro systems are supper fast, pro photographers will still be disappointed with the system performance while running Adobe Photoshop CS 2 (due to Adobe's lack of a universal binary). Rosetta emulation is still slow no matter how fast your computer is. In the case of Photoshop CS/2, MacWorld has the new Mac Pro running at nearly half the speed of a Quad PowerMac.
Interestingly enough, Photoshop CS/2 performance numbers are not much different when comparing a quad-core G5 to a dual-core G5, hummmm.
In any case, the new Mac Pro is significantly faster than my existing crop of G5 and Intel based iMacs and MacBook Pros.