Linux Router distro's with dual stack capability

[Blake Pfankuch <bpfankuch () cpgreeley com>]

Anyone have some insight on a good dual stack Linux (or BSD) router distro?  Currently using IPCop but it lacks ipv6 
support.  I've used SmoothWall Express but not in some time and not sure how well it works with IPv6.  Not looking for 
something huge, just something for the equivalent of a small branch office.  Site to Site VPN support and NAT 
translation capability for a few public IP addresses to private addresses are the only requirements.  Public or private 
responses are welcome!

Thanks!
Blake Pfankuch
Network Engineer