Pacific Science Center
The macro goes to a 1:1 reproduction ratio with an extension tube, but I didn't use it. It'd probably have been touching the butterflies at that point anyway.
UPDATE: We're putting all of our Pacific Science Center pictures here. I've since picked up a Tokina 100mm macro, which, in addition to giving me a bit more working distance, also meters. And mounts, on my D80 (which the Nikkor doesn't).