Just installed NDrive Australia & New Zealand today: http://itunes.apple.com/nz/app/ndrive-australia-new-zealand/id332010002?mt=8

Compatible with iPhone, iPod touch and iPad. Requires iPhone OS 3.0 or later

Great price and app for occasional use.  On special at the moment for $20.99 in the NZ Apple Store.  

Navigation results in the odd 'scenic route' but otherwise it's great for my needs.  Was over $80.00.