Indeed. new iMac and Mac Mini machines using NVidia chipsets are already in the 10.5.6 drivers. It's just a matter of time now. The Mac Pro is probably waiting on the Core i7 based Xeons to come out.

Matt, if you do go with a Mac Pro, make sure you don't gimp it somehow like taking one of the processors off the order. When I bought mine last year, going from 2 2.8ghz chips down to one would have cut $500 off. The Xeon processor alone is at best ~$900 today, and then add in the price of having to get the heatsink for the system.