I'm not sure what the reasons are for NZ and Aus getting some movies earlier, I'm sure it's probably just a clash thing, but it does seem to lend a fair bit of "word of mouth" from the smaller markets.
This could all be specious bollocks, I really don;t know anything about marketing or such, but in the Global Internet age it's easy for a small market (NZ, Aussie) to get word of mouth out about something. The last time I saw this happen was Rise of TPotA. Exactly the same thing.
Obviously the fact that Kiwis and Aussies went in their droves to see this flick suggests that the marketing has done it's job, but the ecstatic reaction can only add to the level of anticipation in the major markets. Just a thought
What I'm really trying to say, is that if they want to release Prometheus here a couple of weeks early, I'll happily be the guinea pig ;p