>Is it possible to run IPv4 out one port and IPv6 out the other?

	IPv4 and IPv6 are separate protocol (like IPv4 and Appletalk)
	on the wire.  They have separate ethernet protocol type number.
	Therefore, you can run:
	- IPv4 and IPv6 on the same wire
	- IPv4 on one interface, and IPv6 on another

	One thing you cannot do is, communicate directly from IPv6-only
	host to IPv4-only host.  There are two answer to this:
	- IPv6-capable hosts must also be IPv4-capable, for early deployment
	  stage.  Therefore, the dual-stack node can use IPv4 when communicating
	  with IPv4-only host.
	- You can have NAT-like translator, or web proxy kind of thing
	  inbetween.  Application proxy works just fine for web proxy
	  and SMTP (sendmail capable of IPv4/v6 will be able to relay your
	  traffic).

	Am I answering your question?

itojun