Great Ape personhood, or at least granting them the right to not have cruel tests done, has been done by several other nations not just New Zealand: http://en.wikipedia.org/wiki/Great_ape_personhood

I can't remember the exact wording but one provision was about how they couldn't be exported unless it was in their best interests. E.g. you can't sell them a circus overseas in which they would likely receive cruel treatment.

So it's not about calling them people, it's about giving them some rights because they have sentience.