nGhost2 works with dual-zone video and audio. Audio is simply a matter of telling the instances of nGhost which audio device to use. I've never tried it, but in theory, that's all it should take.
And although no skin exists for it yet, nGhost can create a control/communication link between all running instances. That way the driver can control the passenger instances.
The Zotac ION does support dual out. But yeah, you'll probably need a dvi lcd. my in-dash xenarc has both. Liliputs are coming out with them in the future.