No Navigation support for New Zealand

Hello friends i have HTC wildfire and when i start my navigation in my cell phone i can see google navigation is not supported in New Zealand.
Can anyone tell me what could be the problem, how can i solve this, do i have to download maps for NZ or wait(but until when). I purchase this cell phone considering GPS navigation system but i haven't used it since i bought it.

Can anyone please help me answer my question

in reference to: Google Maps Navigation for mobile (view on Google Sidewiki)