From a National Library of New Zealand Blog Post by Content Designer,
Everything we’ve uploaded to [the National Library of NZ On The Commons] account is yours to use in whatever way you want. These are images that have no copyright, donor restrictions, or anything else that might get in the way. They’ve also been uploaded at the highest resolution we have.
[Our Emphasis] The new uploads came from our free download pool, which is full of – you guessed it – images you can download for free. So why did I spend far too long writing terrible code to pipe them all up to Flickr?
First, there’s a ton of people on Flickr who are never going to come to our site. Why not get our stuff right in front of their faces?
Secondly, our interface for downloading these images isn’t great. You need to log in with RealMe and take the image you want through our whole image ordering process. On Flickr, zooming in to see details or downloading the size you want is far easier.
The complete blog post has more info about the new images and details (including tech info) about what’s coming next.