Publius:What i've calculated is that maybe 2/3rds of the latency between NZ-US NZ-AS (and im measuring just the latency between the two routers in a traceroute which are on either sides of the undersea cable) is due to physical limitations, but ~1/3rd isn't and it surprises me that its as high as that.
1. Things are unlikely to improve end-to-end latency wise until it is feasible to increase the speed of light inside fiber.
2. You are not measuring what you think you are: "the latency between two routers in a traceroute which are on either sides of the undersea cable". This is just absolutely incorrect.
3. As explained before you are seeing the end-to-end latency to Brisbane due to the topology of the network involved.
4. Don't trust reverse DNS.