In 2006, civil unions became legal. These provided an alternative for both gay and straight couples, and were essentially identical to marriages. I, personally, thought they should have bit the bullet and called it by what it was, but that's a fight for another day.
They're not doing much. In 2006 (the first year tehy were available), there were 374 civil unions. In 2007 there were 316. This represents 1.5% of the number of traditional marriages
No doubt this explains the lack of Biblical inundation as God punishes NZ for its tolerance of sodomy. Mind you, it has rained all weekend, so perhaps Teh Gay can still be blamed.
The number of marriages is slipping, and in 2006 47.2% of NZ kids were born outside a marriage - the word "bastard" has ceased to be an insult here for a long time.
I think the fight over civil unions was a red herring. De facto and temporary arrangements appear to be the trend for the future, which probably doesn't bode well for all sorts of issues.