If you drive/walk/cycle in Australia, or want to travel there to do one of those activities, and you expect to do so with Google’s turn-by-turn Navigation on the Android, then you’re going to be dissapointed.
If you try to use it in Australia, it will tell you that “Google Maps Navigation is not yet available in this location.” I haven’t yet found any information about when (if?) it will be available in Australia. The most I’ve seen from Google is a forum reply when they say they’re glad there is so much interest.
I’m not sure why (technically) it’s not enabled. I presume they are ‘just’ taking the directions given by Google Maps (which works beautifully on the Android) and turning that into the turn-by-turn voice directions. I’d also have been happier if there was some official information telling me that it didn’t work in Australia. I’d still have bought the Galaxy S, but at least I wouldn’t be spending time verifying that it’s “broken” and not just an issue with my phone/set-up/fingers/whatever.
So I’m currently looking into alternatives, though I’m going to be even more peeved if I spend money on a solution, and Google comes through within the next month or so.