I think Xen's PCI passthrough support has been dramatically updated since we wrote about it previously.  Accordingly, we too will update dramatically!

(A review: the PCI passthrough allows the administrator to forward a PCI device to a domU.  Once upon a time it was necessary to boot with the PCI device hidden from the dom0 -- this may no longer be the case.  Hard to say.)

Of course, if we had some VT-d hardware we could test that, too.  *sigh*