well, as of now there's no 'officiall' nat. Lots of people are upset about this, so it may change. there are already IPv6 NAT devices being built, but NAT doesn't exist in the IPv6 standard. One of the ideas behing IPv6 was to make sure there are enough addresses available so that nat isn't needed. NAT really is kind of a pain in the ass.
remember, nat was first introduced as a workaround for the lack of IPv4 addresses available...an unintended benefit is the security.