Here's the full text of a statement from Samsung about its plans:
Samsung Electronics Australia is excited at the prospect of bringing the Nexus S to Australia. We are currently reviewing our options on how to bring this to market locally and look forward to sharing more details at a later stage.
In practice, that might mean a six-month delay similar to what we saw with the Nexus One, though Google's own withdrawal from phone distribution might speed the carrier negotiation process. Vodafone sold out of its limited Nexus One stock pretty quickly, so hopefully that will convince it or another carrier to sign up.