I will try to add things here on the system I tested with and systems from friends who are running ZETA on their system's.

Pentium and AMD seem to be fully supported now (tested up to Pentium 4 2.4Ghz and an AMD 2800+). SATA seems to be a problem still, I try'd to boot from a P4 3Ghz system with SATA with no luck at  the moment (no IDE drives in the system).

The intel chipset in combination with AC97' or Live 5.1 doesn't give any problem, on the otherhand the via chipsets can be a bit tricky to get to work (mostly sound related). 

Graphics is no problem for Radeon or Nvidia chipsets/cards.
I still can't get S3 to go here ...

Networking should be fairly easy to setup. The normal LAN connections should be no problem, if you use wireless you should check for drivers if you have no luck. The Orinoco wavelan card I have here is no problem, centrino should be supported but I've heard of people that are working on solutions for some cards there.

USB hardware is very much improved ... I can use all the usb-sticks here (even the mp3 player), only the printer/usb webcam and the external hd don't. The external DVD burner is working nice and even a small usb hub is working great. The two usb camera's I have here are both supported (hp318 and Fuji Finepix S5500).

A lot is done to support current hardware so I think that for those with not to extreme hardware it won't be a problem to run ZETA.