If you are in the market for a PowerMac, now is not the time to buy unless 1) you need the machine now and can not wait, and 2) you don't have any problem spending $2000 now, only to have a completely faster machine available in 3 weeks.
New PowerMacs are coming at Macworld Expo. It's about the only certainty (other than Jobs keynote using the phrase "best thing we've ever done). What the CPU speeds will be is anyone's guess, but you can almost bank of DDR SDRAM on the motherboard, a faster bus, 8xAGP, and a new form factor for the case (which is now 3.5 years old - extremely ripe for a new form factor). The top end should be at least a dual 1.4ghz, if not faster. The Superdrive should be in the mid and highend models, with it possibly debuting in the low end model as well (if the $1799 iMac can sport a Superdrive, it seems silly not to put it in the $1699 monitorless entry level PowerMac).
Hopefully, Apple will have something up their sleeve with regard to the graphics cards. They really need a workstation class 3D card, at least as an option. The GeForce4 Titanium is a great 3D card for gaming, but it's not good enough for anything other than entry level 3D.