Well, my initial attempts at using it find a newly created paravirtual domU (debootstrap'ed Debian etch) seems to currently be suffering from a lack of PCI devices, as made apparent by the message:
PCI: Fatal: No config space access function found
Judging by a few google searches.. it would appear that I'm not the first one to have this problem, although I haven't yet found a solution.. I must be missing some kernel option.
If anyone has any suggestions, I'd be welcome to them... I've attached a (gzipped) copy of my kernel configuration. I *thought* I had selected everything for combined dom0/domU operation (also note- this is my 2nd attempted kernel for domU on 2.6.22-- the first one had a PCI access mode of "ANY" which I changed in the attached config to "Xen PCI Frontend").